Process for producing chlorine

ABSTRACT

A process for producing chlorine by oxidizing hydrogen chloride with oxygen. The process uses various supported ruthenium catalysts or a catalyst system containing (A) an active component of a catalyst and (B) a compound having thermal conductivity of a solid phase measured by at least one point within a range from 200 to 500° C. of not less than 4 W/m. ° C.  
     Specifically, in the drafted Abstract, we proposed to delete the detailed description of various supported ruthenium catalysts which is present on pages 12 and 13 of the specification and in Claim  1.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of Application No. 09/249,100 filed Feb. 12, 1999;the disclosure of the above noted prior application incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing chlorine. Moreparticularly, the present invention relates to a process for producingchlorine by oxidizing hydrogen chloride with oxygen, wherein saidprocess can produce chlorine by using a catalyst having high activity ina smaller amount at a lower reaction temperature. The above inventionalso relates to a process for producing chlorine by oxidizing hydrogenchloride, wherein said process can facilitate control of the reactiontemperature by making it easy to remove the reaction heat from catalystbed using a catalyst having good thermal conductibility, which can beformed by containing a compound having high thermal conductivity of asolid phase, and can achieve high reaction conversion by keeping thewhole catalyst bed at sufficient temperature for industrially desirablereaction rate.

The present invention also relates to a process for producing asupported ruthenium oxide catalyst. More particularly, the presentinvention relates to a process for producing a supported ruthenium oxidecatalyst, wherein said process is a process for producing a catalysthaving high activity and can produce a catalyst having high activitycapable of producing the desired compound by using a smaller amount ofthe catalyst at a lower reaction temperature.

Furthermore, the present invention relates to a supported rutheniumoxide catalyst. The present invention relates to a supported rutheniumoxide catalyst, wherein said catalyst has high activity and can producethe desired compound by using a smaller amount of the catalyst at alower reaction temperature.

2. Description of the Related Art

It is well known that chlorine is useful as a raw material of vinylchloride, phosgene, etc., and can be produced by oxidizing hydrogenchloride. For example, the Deacon reaction by using a Cu catalyst iswell known. For example, British Patent No. 1,046,313 discloses aprocess for oxidizing hydrogen chloride by using a catalyst containing aruthenium compound, and also discloses that ruthenium (III) chloride isparticularly effective among the ruthenium compounds. Furthermore, aprocess for supporting a ruthenium compound on a carrier is alsodisclosed and, as the carrier, silica gel, alumina, pumice and ceramicmaterial are exemplified. As the Example, a ruthenium chloride catalystsupported on silica is exemplified. However, a test was conducted usinga catalyst prepared by using a process for preparing a ruthenium (III)chloride supported on silica disclosed in said patent publication. As aresult, the ruthenium compound as a catalyst component is drasticallyvolatilized and it was disadvantageous for industrial use. For example,European Patent EP-0184413A2 discloses a process for oxidizing hydrogenchloride by using a chromium oxide catalyst. However, conventionallyknown processes had a problem that the activity of the catalyst isinsufficient and high reaction temperature is required.

When the activity of the catalyst is low, a higher reaction temperatureis required but the reaction of oxidizing hydrogen chloride with oxygento produce chlorine is an equilibrium reaction. When the reactiontemperature is high, it becomes disadvantageous in view of equilibriumand the equilibrium conversion of hydrogen chloride decreases.Therefore, when the catalyst has high activity, the reaction temperaturecan be decreased and, therefore, the reaction becomes advantageous inview of equilibrium and higher conversion of hydrogen chloride can beobtained. In case of the high reaction temperature, the activity islowered by volatilization of the catalyst component. Also in this pointof view, it has been required to develop a catalyst which can be used atlow temperature.

Both high activity per unit weight of catalyst and high activity perunit weight of ruthenium contained in the catalyst are required to thecatalyst, industrially. Since high activity per unit weight of rutheniumcontained in the catalyst can reduces the amount of ruthenium containedin the catalyst, it becomes advantageous in view of cost. It is possibleto select the reaction condition which is more advantageous in view ofequilibrium by conducting the reaction at a lower temperature using acatalyst having high activity. It is preferred to conduct the reactionat a lower temperature in view of stability of the catalyst.

The catalyst used in the oxidizing reaction of hydrogen chlorideincludes, for example, a supported ruthenium oxide catalyst prepared bysupporting ruthenium chloride on a carrier, drying the supported one,heating in a hydrogen gas flow to form a supported metal rutheniumcatalyst, and oxidizing the catalyst. When ruthenium chloride is reducedwith hydrogen, sintering of ruthenium occurs, which results in decreaseof activity of the resulting catalyst.

A process for preparing ruthenium oxide supported on a carrier withoutcausing sintering of ruthenium during the preparation step of a catalystis preferred. First, a process has been desired which is not a processfor reducing at high temperature by using hydrogen, but a process forpreparing ruthenium oxide on a carrier with preventing sintering bytreating a ruthenium compound with a mixture of a basic compound and areducing compound, or a mixture of an alkali compound and a reducingcompound, and oxidizing the treated one.

Second, a process has been desired which is a process for preparingruthenium oxide on a carrier with preventing sintering by oxidizingafter passing through a state of an oxidation number of 1 to less than 4valence without preparing a ruthenium compound having an oxidationnumber of 0 valence by completely reduction

Third, it has been desired to develop a catalyst preparing process whichcan obtain a highly active hydrogen chloride oxidizing catalyst bypassing through a preparation of a highly dispersed supported metalruthenium catalyst, when the preparation is carried out by supporting aruthenium compound on a carrier, reducing the supported one in order toprepare supported metal ruthenium catalyst, and oxidizing to prepare asupported ruthenium oxide catalyst.

A supported ruthenium oxide catalyst obtained by using an anatasecrystalline or non-crystalline titanium oxide as a carrier was highlyactive to oxidation of hydrogen chloride, but it has been required todevelop a catalyst having higher activity.

In the case of a conventional carrier which the content of an OH groupon the surface of titanium oxide is too large or small, a catalysthaving high activity was not obtained and the catalytic activitydecreased sometimes as time passed.

When the oxidizing reaction of hydrogen chloride is conducted at ahigher reaction rate with conventionally known catalysts, heat generatedas a result of the high reaction rate can not be sufficiently removedand the temperature of the catalyst bed increases locally and,therefore, the reaction temperature can not be easily controlled.

Furthermore, when the reaction is conducted by using these catalysts, alarge temperature distribution occurs in the catalyst bed and it isimpossible to keep the whole system at sufficient temperature forindustrially desirable reaction rate without exceeding upper temperaturelimit for keeping high catalyst activity. Therefore, the reactionconversion is lowered.

As a process for increasing the rate of removing heat generated duringthe reaction, for example, a process for increasing a heat transfer areain contact with external coolant per volume of the catalyst bed isknown. However, when the heat transfer area becomes large, the cost of areactor increases. On the other hand, when heat is removed by coolingthe catalyst bed from outside, heat transfers to an external coolantthrough the catalyst bed and the heat transfer surface. When the thermalconductivity of the catalyst is improved, the heat removing rateincreases. Therefore, it has been required to develop a catalyst havinggood thermal conductibility, which can increase the heat removing rate,to avoid difficulty of control of the reaction temperature.

It is generally considered that, when a carrier supporting an activecomponent of the catalyst is mixed with an inactive component at theratio of 1:1, the activity per volume or per weight reduced to half.Therefore, it is required to develop a catalyst having good thermalconductivity as described above and further to develop a catalyst havinghigh activity which the activity of the catalyst per volume or perweight does not decrease.

It is known that, since a supported catalyst is generally prepared bysupporting on a carrier having porediameters of from 30 to 200angstroms, the rate-determining step of the reaction is controlled bythe catalyst pore diffusion control and it is difficult to improve theactivity of the catalyst. Therefore, it has been required to develop acatalyst having macropores which the inside of the catalytic particlescan be utilized

As a result, since the reaction proceeds in the vicinity of the outersurface of the catalytic particles, it is considered that rutheniumoxide supported on the outer surface of the carrier is used in thereaction but ruthenium oxide supported in the catalytic particles is notused in the reaction. Therefore, it has been required to develop acatalyst obtained by supporting ruthenium oxide on the outer surface ofthe catalyst.

It is also known that a ruthenium oxide catalyst is useful as a catalystin process for preparing chlorine by an oxidizing reaction of hydrogenchloride and is obtained by hydrolyzing ruthenium chloride, oxidizingthe hydrolyzed one, and calcining the oxidized one. For example,European patent EP-0743277A1 discloses that a ruthenium oxide catalystsupported on titanium oxide is obtained by hydrolyzing a rutheniumcompound by using an alkali metal hydroxide, supporting the hydrolyzedone on titanium hydroxide, and calcining the supported one under air.The present inventors have found that the supported ruthenium oxidecatalyst is obtained by oxidizing a supported metal ruthenium catalyst.As a process for preparing the supported metal ruthenium catalyst, forexample, it is known that a process for preparing a supported metalruthenium catalyst by supporting ruthenium chloride on a carrier, dryingthe supported one, and heating the dried one in a hydrogen gas flow.However, there was a problem that a supported ruthenium oxide catalystprepared by oxidizing a catalyst reduced by hydrogen has low activitydue to sintering of ruthenium when ruthenium chloride is reduced withhydrogen.

A process for preparing ruthenium oxide supported on a carrier withpreventing sintering has been required. First, a process has beendesired which is not a process for reducing at high temperature by usinghydrogen, but for treating a ruthenium compound with a mixture of areducing compound and a basic compound, or a mixture of an alkalicompound and a reducing compound, and oxidizing the treated one.

Second, a process has been desired which is a process for preparingruthenium oxide on a carrier with preventing sintering by oxidizingafter passing through a state of an oxidation number of 1 to less than 4valence without preparing a ruthenium compound having an oxidationnumber of 0 valence by completely reduction.

In general, it is difficult to reduce the ruthenium compound with areducing compound, unlike platinum and palladium. For example, becauseof this , there is a problem that a supported ruthenium oxide catalystprepared by oxidizing after adding hydrazine to ruthenium chloride haslow activity because of a formation of complex by adding hydrazine toruthenium chloride.

A supported ruthenium oxide catalyst obtained by using an anatasecrystalline or non-crystalline titanium oxide as a carrier was highlyactive to oxidation of hydrogen chloride, but it has been required todevelop a catalyst having higher activity.

In the case of a content of an OH group on the surface of titanium oxidewhich is a conventional carrier is too large or small, a catalyst havinghigh activity was not obtained and the catalytic activity decreasedsometimes as time passed.

It is known that the rate-determining step of the reaction is under thecatalyst pore diffusion control and it is difficult to improve theactivity of the catalyst since a supported catalyst is generallyprepared by supporting on a carrier having pore diameters of from 30 to200 angstroms. As a result, it is considered that ruthenium oxidesupported on the outer surface of the carrier is used in the reactionbut ruthenium oxide supported in the catalytic particles is not used inthe reaction since the reaction proceeds in the vicinity of the outersurface of the catalytic particles. Therefore, it has been required todevelop a technique for supporting ruthenium oxide on the outer surfaceof the catalyst.

SUMMARY OF THE INVENTION

It is an object of the present invention is to provide a process forproducing chlorine by oxidizing hydrogen chloride with oxygen, whereinsaid process can produce chlorine by using a catalyst having highactivity in a smaller amount at a lower reaction temperature. One of theabove object of the present invention to provide a process for producingchlorine by oxidizing hydrogen chloride, wherein said process canfacilitate control of the reaction temperature by making it easy toremove the reaction heat from catalyst bed using a catalyst having goodthermal conductivity, which can be formed by containing a compoundhaving high thermal conductivity in solid phase, and can attain highreaction conversion by keeping the whole catalyst bed at sufficienttemperature for industrially desirable reaction rate capable ofoxidizing hydrogen chloride.

It is still another object of the present invention to provide a processfor producing a supported ruthenium oxide catalyst, characterized inthat said process is a process for producing a catalyst having highactivity and can produce a catalyst having high activity capable of thedesired compound using a smaller amount of a catalyst at a lowerreaction temperature.

It is a further object of the present invention to provide a supportedruthenium oxide catalyst, characterized in that said catalyst has highactivity and can produce the desired compound using a smaller amount ofa catalyst at a lower reaction temperature.

That is, the present invention relates to a process for producingchlorine by oxidizing hydrogen chloride with oxygen, wherein saidprocess uses one catalyst selected from the following catalysts (1) to(9):

(1) a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, treating thesupported one by using a basic compound, treating by using a reducingcompound, and oxidizing;

(2) a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing agent to form ruthenium having anoxidation number of 1 to less than 4 valence, and oxidizing;

(3) a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, reducing thesupported one by using a reducing hydrogenated compound, and oxidizing;

(4) a supported ruthenium oxide catalyst obtained by using titaniumoxide containing rutile titanium oxide as a carrier;

(5) a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing compound or reducing agent in a liquidphase, and oxidizing, wherein titanium oxide contains an OH group in anamount of 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier) per unit weight of acarrier;

(6) a catalyst system containing the following components (A), and notless than 10% by weight of component (B):

(A) an active component of catalyst;

(B) a compound wherein thermal conductivity of a solid phase measured byat least one point within a range from 200 to 500° C. is not less than 4W/m. ° C.;

(7) a supported ruthenium oxide catalyst having a macro pore with a poreradius of 0.03 to 8 micrometer;

(8) an outer surface-supported catalyst obtained by supporting rutheniumoxide on a carrier at the outer surface; and

(9) a supported ruthenium catalyst obtained by using chromium oxide as acarrier.

The present invention also relates to a process for producing asupported ruthenium oxide catalyst selected from the following processes(1) to (5):

(1) a process for producing a supported ruthenium oxide catalyst, whichcomprises the steps of supporting a ruthenium compound on a carrier,treating the supported one by using a basic compound, treating by usinga reducing compound, and oxidizing;

(2) a process for producing a supported ruthenium oxide catalyst, whichcomprises the steps of supporting a ruthenium compound on a carrier,treating the supported one by using a reducing compound to formruthenium having an oxidation number of 1 to less than 4 valence, andoxidizing;

(3) a process for producing a supported ruthenium oxide catalyst, whichcomprises the steps of supporting a ruthenium compound on a titaniumoxide carrier containing rutile titanium oxide, treating the supportedone by using a reducing agent, and oxidizing;

(4) a process for producing a supported ruthenium oxide catalyst, whichcomprises the steps of supporting a ruthenium compound on a titaniumoxide carrier containing an OH group in an amount of 0.1×10⁻⁴ to 30×10⁻⁴(mol/g-carrier) per unit weight of a carrier, treating the supported oneby using a reducing agent, and oxidizing; and

(5) a process for producing a supported ruthenium oxide catalystcontaining ruthenium oxide only at an outer surface layer, not less than80% of the outer surface of said catalyst satisfying the followingexpression (1):S/L<0.35  (1)wherein L is a distance between a point (A) and a point (B), said point(B) being a point formed on the surface of a catalyst when aperpendicular line dropped from any point (A) on the surface of thecatalyst to the inside of the catalyst goes out from the catalyst at theopposite side of the point (A), and S is a distance between the point(A) and a point (C), said point (C) being a point on the perpendicularline where ruthenium oxide does not exist, wherein said processcomprises supporting an alkali on a carrier, supporting at least oneruthenium compound selected from the group consisting of rutheniumhalide, rutheniumoxy chloride, ruthenium-acetylacetonato complex,ruthenium organic acid salt and ruthenium-nitrosyl complex on thecarrier, treating by using a reducing agent, and oxidizing.

The present invention also relates to a supported ruthenium oxidecatalyst obtained by supporting on a titanium oxide carrier containingnot less than 20% by weight of rutile titanium oxide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The supported ruthenium oxide catalyst (1) used in the present inventionis a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, treating thesupported one by using a basic compound, treating by using a reducingcompound, and oxidizing the resulting one. In general, said catalyst isindustrially used in the form of being supported on a carrier.

The supported ruthenium oxide catalyst (2) used in the present inventionis a supported ruthenium oxide catalyst obtained by the steps whichcomprises supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing agent to form ruthenium having anoxidation number of 1 to less than 4 valence, and oxidizing theresulting one.

The process for preparing the supported ruthenium oxide catalyst used inthe oxidizing reaction of hydrogen chloride include various processes.For example, a process for preparing a catalyst comprising rutheniumoxide having an oxidation number of 4 valence supported on a carrier canbe prepared by supporting ruthenium chloride on a carrier, hydrolyzingthe supported one by using an alkali, and calcining under an air.Alternatively, a process for preparing a catalyst comprising supportedruthenium oxide having an oxidation number of 4 valence can also beprepared by supporting ruthenium chloride on a carrier, reducing thesupported one by using various reducing agents to form ruthenium havinga valence of 0, and calcining under an air. It is also possible toexemplify a preparation example of a supported ruthenium oxide catalystcomprising supported ruthenium oxide having an oxidation number of 4,which is prepared by supporting ruthenium chloride on a carrier,treating the supported one by using a mixed solution of various reducingcompounds and basic compounds, or treating by using an aqueous alkalisolution of a reducing compound, or treating by using various reducingagents, thereby to form a ruthenium compound having an oxidation numberof 1 to less than 4 valence, and calcining under an air. The catalystprepared by this preparation process can be exemplified as a preparationexample which is most active to the oxidizing reaction of hydrogenchloride. The process of adjusting the oxidation number of the rutheniumcompound supported on the carrier within a range from 1 to less than 4valence includes various processes, for example, process of treating byusing a mixed solution of a reducing compound and a basic compound,process of treating by using an alkali solution of a reducing compound,process of treating by using an organolithium compound, an organosodiumcompound or an organopotassium compound, process of treating by using anorganoaluminum compound, process of treating by using an organomagnesiumcompound, and process of treating by using hydrogen. When using thesereducing agents in an excess amount, the ruthenium compound is reducedto the valence of 0 and, therefore, it is necessary to use a suitableamount.

The process of measuring the oxidation number of the supported rutheniumincludes various processes. For example, since nitrogen is mainlygenerated when using hydrazine as the reducing agent, the valence numberof ruthenium can be determined by the amount of nitrogen generated.

The reaction scheme will be shown below.

For example, when the ruthenium compound is reduced by using hydrazineunder the conditions of an aqueous alkali solution, a hydroxide ofruthenium is formed. Therefore, the oxidation number of ruthenium can bedetermined by measuring a ratio of ruthenium to oxygen or chlorinebinding to ruthenium due to elemental analysis after dehydration undervacuum. When using ruthenium chloride as the ruthenium compound, ahydroxide and a chloride of ruthenium are formed. Therefore, theoxidation number of ruthenium can also be determined by measuring aratio of ruthenium to oxygen and chlorine binding to ruthenium due toelemental analysis after dehydration under vacuum.

In the present invention, the oxidation number of ruthenium wasdetermined from the amount of nitrogen generated by using the scheme(1).

The common part with the catalysts (1) and (2) will be explained.

The carrier includes, for example, oxides and mixed oxides of elements,such as titanium oxide, alumina, zirconium oxide, silica, titanium mixedoxide, zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxideand the like. Preferable carriers are titanium oxide, alumina, zirconiumoxide and silica, and more preferable carrier is titanium oxide.

The ruthenium compound to be supported on the carrier include compounds,for example, ruthenium chloride such as RuCl₃ and RuCl₃ hydrate;chlororuthenate such as K₃RuCl₆, [RuCl₆]³⁻ and K₂RuCl₆; chlororuthenatehydrate such as [RuCl₅(H₂O)₄]²⁻ and [RuCl₂(H₂O)₄]⁺; salt of ruthenicacid, such as K₂RuO₄; rutheniumoxy chloride such as Ru₂OCl₄, Ru₂OCl₅ andRu₂OCl₆; salt of rutheniumoxy chloride, such as K₂Ru₂OCl₁₀ andCsRu₂OCl₄; ruthenium-ammine complex such as [Ru(NH₃)₆]²⁺, [Ru(NH₃)₆]³⁺and [Ru(NH₃)₅H₂O]²⁺; chloride and bromide of ruthenium-ammine complex,such as [Ru(NH₃)₅Cl]²⁺, [Ru(NH₃)₆] Cl₂, [Ru(NH₃)₆]Cl₃ and [Ru(NH₃)₆]Br₃;ruthenium bromide such as RuBr₃ and RuBr₃ hydrate; otherruthenium-organoamine complex; ruthenium-acetylacetonato complex;ruthenium-carbonyl complex such as Ru(CO)₅ and [Ru₃(CO)₁₂; rutheniumorganic acid salt such as Ru₃O(OCOCH₃)₆(H₂O)₃])OCOCH₃ hydrate andRu₂(RCOO)₄Cl(R=C1-3 alkyl group); ruthenium-nitrosyl complex such asK₂[RuCl₅(NO)]], [Ru(NH₃)₅(NO)]Cl₃, [Ru(OH) (NH₃)₄(NO)] (NO₃)₂ and Ru(NO)(NO₃)₃, and ruthenium-phosphine complex. Preferable compounds areruthenium halide compounds, for example, ruthenium chloride such asRuCl₃ and RuCl₃ hydrate and ruthenium bromide such as RuBr₃ and RuBr₃hydrate. More preferred one is a ruthenium chloride hydrate.

The process of supporting the ruthenium compound on the carrierincludes, for example, impregnation process and equilibrium adsorptionprocess.

The reducing compound used for treating the ruthenium compound supportedon the carrier includes, for example, hydrazine, methanol, ethanol,formaldehyde, hydroxylamine or formic acid, or an aqueous solution ofhydrazine, methanol, ethanol, formaldehyde, hydroxylamine or formicacid, or a solution of an organic solvent such as alcohol. Preferred arehydrazine, methanol, ethanol, formaldehyde, and solutions of hydrazine,methanol, ethanol and formaldehyde. More preferred are hydrazine and asolution of hydrazine. The reducing compound used for treating theruthenium compound supported on the carrier includes, for example, acompound having a redox potential of −0.8 to 0.5 V, a solution thereof,and a solution of an organic solvent such as alcohol. Now a standardelectrode potential is used in place of the redox potential. Among thecompounds listed above, a standard electrode potential of hydrazine is−0.23 V, that of formaldehyde is 0.056 V and that of formic acid is−0.199 V, respectively. It is also a preferable process to use anaqueous alkali solution of the reducing compound.

The basic compound listed as the catalyst (1) includes, for example,ammonia; amine such as alkyl amine, pyridine, aniline, trimethylamineand hydroxyl amine; alkali metal hydroxide such as potassium hydroxide,sodium hydroxide and lithium hydroxide; alkali metal carbonate such aspotassium carbonate, sodium carbonate and lithium carbonate; andhydroxide of quaternary ammonium salt.

The basic compound for preparing the catalyst (2) includes, for example,ammonia; amine such as alkyl amine, pyridine, aniline, trimethylamineand hydroxyl amine; alkali metal hydroxide such as potassium hydroxide,sodium hydroxide and lithium hydroxide; alkali metal carbonate such aspotassium carbonate, sodium carbonate and lithium carbonate; hydroxideof quaternary ammonium salt; and alkyl aluminum such as triethylaluminum.

The process of treating the ruthenium compound supported on the carrierby using a reducing compound includes, for example, a process ofsupporting a ruthenium compound on a carrier, drying the supported one,and dipping the dried one in a reducing compound or a solution of areducing compound, or impregnating with a reducing compound or asolution of a reducing compound. A process of dipping in an alkalisolution of a reducing compound is also a preferable process.

A process of treating by using a reducing compound or an alkali solutionof the reducing compound, and adding an alkali metal chloride is also apreferable process.

The process of oxidizing includes, for example, process of calciningunder air.

A weight ratio of ruthenium oxide to the carrier is preferably within arange from 0.1/99.9 to 20.0/80.0, more preferably from 0.5/99.5 to15.0/85.0, and most preferably from 1.0/99.0 to 15.0/85.0. When theratio of ruthenium oxide is too low, the activity is lowered sometimes.On the other hand, when the ratio of ruthenium oxide is too high, theprice of the catalyst becomes high sometimes. Examples of the rutheniumoxide to be supported include ruthenium dioxide, ruthenium hydroxide andthe like.

The embodiment of the process for preparing the supported rutheniumoxide catalyst used in the present invention include a preparationprocess comprising the following steps:

a ruthenium compound supporting step: step of supporting a rutheniumcompound on a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium compound supporting step;

a reducing compound treating step: step of treating one obtained in thealkali treating step by using a reducing compound; and

an oxidizing step: step of oxidizing one obtained in the reducingcompound treating step.

It is also preferred to use an aqueous alkali solution of a reducingcompound to simultaneously conduct the alkali treating step and thereducing compound treating step in the above step.

Preferred embodiment of the process of preparing the supported rutheniumoxide catalyst used in the present invention include a preparationprocess comprising the following steps:

a ruthenium halide compound supporting step: step of supporting aruthenium halide compound on a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide compound supporting step;

a reducing compound treating step: step of treating one obtained in thealkali treating step by using hydrazine, methanol, ethanol orformaldehyde; and

an oxidizing step: step of oxidizing one obtained in the reducingcompound treating step.

It is also preferred to use an aqueous alkali solution of a reducingcompound to simultaneously conduct the alkali treating step and thereducing compound treating step in the above step.

More preferred embodiment of the process of preparing the supportedruthenium oxide catalyst used in the present invention include apreparation process comprising the following steps:

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide supporting step;

a hydrazine treating step: step of treating one obtained in the alkalitreating step by using hydrazine; and

an oxidizing step: step of oxidizing one obtained in the hydrazinetreating step.

It is also preferred to use an aqueous alkali solution of a hydrazine tosimultaneously conduct the alkali treating step and the hydrazinetreating step in the above step.

More preferred embodiment of the process of preparing the supportedruthenium oxide catalyst used in the present invention include apreparation process comprising the following steps:

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide supporting step;

a hydrazine treating step: step of treating one obtained in the alkalitreating step by using hydrazine;

an alkali metal chloride adding step: step of adding an alkali metalchloride to one obtained in the hydrazine treating step; and

an oxidizing step: step of oxidizing one obtained in the alkali metalchloride adding step.

It is also preferred to use an aqueous alkali solution of hydrazine tosimultaneously conduct the alkali treating step and the hydrazinetreating step in the above step.

The ruthenium halide supporting step is a step of supporting rutheniumhalide on a carrier of a catalyst. The ruthenium compound to besupported on the carrier includes, for example, already listed variousruthenium compounds. Among them, preferred examples thereof are halidesof ruthenium, for example, ruthenium chloride such as RuCl₃ and RuCl₃hydrate and ruthenium bromide such as RuBr₃ and RuBr₃ hydrate. Morepreferred one is a ruthenium chloride hydrate.

The amount of ruthenium halide used in the ruthenium halide supportingstep is usually an amount corresponding to a preferable weight ratio ofruthenium oxide to the carrier. That is, ruthenium halide is supportedby using a process of impregnating an already listed carrier of thecatalyst, or a process of performing equilibrium adsorption. As thesolvent, for example, water and an organic solvent such as alcohol areused, and water is preferred. The impregnated one can be dried, and canalso be treated by using an alkali without being dried, but it ispreferable the impregnated one is dried. Regarding the conditions fordrying the impregnated one, the drying temperature is preferably from 50to 200° C. and the drying time is preferably from 1 to 10 hours.

The alkali treating step is a step for adding an alkali to one obtainedin the ruthenium halide supporting step. The alkali used in the alkalitreating step includes, for example, hydroxide, carbonate andhydrogencarbonate of alkali metal; aqueous solution of ammonia, ammoniumcarbonate and ammonium hydrogencarbonate; and solution of an organicsolvent such as alcohol. As the alkali, for example, hydroxide,carbonate and hydrogencarbonate of alkali metal are preferably used. Asthe solvent, for example, water is preferably used. The concentration ofthe alkali varies depending on the alkali to be used, but is preferablyfrom 0.1 to 10 mol/l.

Regarding a molar ratio of the ruthenium halide to alkali is, forexample, 3 mol of sodium hydroxide is equivalent to 1 mol of rutheniumhalide. Preferably, the alkali is used in the amount of 0.1-20equivalent per equivalent of ruthenium halide. The process of adding thealkali include a process of impregnating with a solution of the alkalior a process of dipping in a solution of the alkali. The time ofimpregnation with the solution of the alkali is usually within 60minutes. Since the activity of the catalyst decreases when theimpregnation time is long, the impregnation time is preferably within 10minutes. The temperature is preferably from 0 to 100° C., and morepreferably from 10 to 60° C.

The hydrazine treating step is a step of treating one obtained in thealkali treating step by using hydrazine. The process of treating byusing hydrazine includes, for example, a process of impregnating with asolution of hydrazine and a process of dipping in a solution ofhydrazine. The supported ruthenium halide treated by using the alkali inthe previous step and an alkali solution may be added to a hydazinesolution in a state of being mixed, or may be added to the hydazinesolution after the alkaline solution was separated by filtration. Apreferable process is a process of impregnating the supported rutheniumhalide with the alkali and immediately adding to the hydrazine solution.The concentration of hydrazine used in the hydrazine treating step ispreferably not less than 0.1 mol/l. Hydrazine hydrate such as hydrazinemonohydrate may be used as it is. Alternatively, it is used as asolution of an organic solvent such as alcohol. Preferably, an aqueoussolution of hydrazine or hydrazine hydrate is used. Anhydride and amonohydrate of hydrazine can also be used. Regarding a molar ratio ofruthenium halide to hydrazine, hydrazine is used in the amount of 0.1 to20 mol per mol of ruthenium halide. The time of impregnation with thesolution of hydrazine is preferably from 5 minutes to 5 hours, and morepreferably from 10 minutes to 2 hours. The temperature is preferablyfrom 0 to 100° C., and more preferably from 10 to 60° C. After dippingin the hydrazine solution, the dipping one is preferably separated fromthe solution by filtration.

It is also preferred to use an aqueous alkali solution of hydrazine tosimultaneously conduct the alkali treating step and hydrazine treatingstep in the above step. Preferable process includes a process of slowlydipping one obtained in the ruthenium halide supporting step to thoseprepared by mixing a preferable amount of the alkali with a preferableamount of hydazine, and treating for 5 minutes to 5 hours.

More preferable process includes a process of washing a solid producedin the alkali treating step and hydrazine treating step, thereby toremove the alkali and hydrazine, drying, adding an alkali metal chloridein the following alkali metal chloride adding step, drying, andoxidizing.

More preferable process includes a process of washing a solid producedin the alkali treating step and hydrazine treating step by using anaqueous solution of an alkali metal chloride, drying, and oxidizing.This process is preferred because the removal of the alkali andhydrazine, and the addition of the alkali metal chloride can beconducted in the same step.

The alkali metal chloride adding step is a step of adding an alkalimetal chloride to one obtained in the alkali treating step and hydrazinetreating step. This step is not an indispensable step to prepare thesupported ruthenium oxide catalyst, but the activity of the catalyst isfurther improved by conducting said step. That is, the resulting solidis oxidized by the following oxidizing step, but it is a preferablepreparation example to convert it into highly active supported rutheniumoxide by oxidizing the resulting solid treated with the alkali andhydrazine in the presence of an alkali metal salt.

The alkali metal chloride includes, for example, chloride of alkalimetal, such as potassium chloride and sodium chloride. Preferablealkaline metal chlorides are potassium chloride and sodium chloride, andmore preferable one is potassium chloride. A molar ratio of the alkalimetal salt to ruthenium is preferably from 0.01 to 10, and morepreferably from 0.1 to 5.0. When the amount of the alkali metal saltused is too small, sufficient highly active catalyst is not obtained. Onthe other hand, when the amount of the alkali metal salt used is toolarge, the cost becomes high from an industrial point of view.

The process of adding the alkali metal chloride includes a process ofimpregnating the resulting supported ruthenium one, obtained by washing,drying, treating by using an alkali and hydrazine, with an aqueoussolution of the alkali metal chloride, but more preferable processincludes a process of impregnating the resulting supported ruthenium onetreated with the alkali and hydrazine by washing with an aqueous alkalimetal chloride solution without being washed with water.

For the purpose of adjusting the pH in the case of washing the resultingsupported one, hydrochloric acid can be added to an aqueous solution ofthe alkali metal chloride. The concentration of the aqueous solution ofthe alkali metal chloride is preferably from 0.01 to 10 mol/l, and morepreferably from 0.1 to 5 mol/l.

The purpose of washing lies in removal of the alkali and hydrazine, butthe alkali and hydrazine can also be remained as far as the effect ofthe present invention is not adversely affected.

After impregnating with the alkali metal chloride, the catalyst isusually dried. Regarding the drying conditions, the drying temperatureis preferably from 50 to 200° C. and the drying time is preferably from1 to 10 hours.

The oxidizing step is a step of oxidizing one obtained in the alkalitreating step and hydrazine treating step (in the case of using noalkali metal chloride adding step), or a step of oxidizing one obtainedin the alkali metal chloride adding step (in the case of using thealkali metal chloride adding step). The oxidizing step can include aprocess of calcining under an air. It is a preferable preparationexample to convert it into highly active supported ruthenium oxide bycalcining one treated with the alkali and hydrazine in the presence ofan alkali metal salt, in a gas containing oxygen. A gas containingoxygen usually includes air.

The calcination temperature is preferably from 100 to 600° C., and morepreferably from 280 to 450° C. When the calcination temperature is toolow, particles formed by the alkali treatment and hydrazine treatmentare remained in a large amount in the form of a ruthenium oxideprecursor and, therefore, the activity of the catalyst becomesinsufficient sometimes. On the other hand, when the calcinationtemperature is too high, agglomeration of ruthenium oxide particlesoccur and, therefore, the activity of the catalyst is lowered. Thecalcination time is preferably from 30 minutes to 10 hours.

In this case, it is important to calcine in the presence of the alkalimetal salt. By using this process, it is possible to obtain higheractivity of the catalyst because that process can form more fineparticles of ruthenium oxide, comparing the process which includescalcining in the substantially absence of the alkali metal salt.

By the calcination, the particles supported on the carrier, which areformed by the alkali treatment and hydrazine treatment, are convertedinto a supported ruthenium oxide catalyst. It can be confirmed byanalysis such as X-ray diffraction and XPS (X-ray photoelectronspectroscopy) that the particles formed by the alkali treatment andhydrazine treatment were converted into ruthenium oxide. Incidentally,substantially total amount of particles formed by the alkali treatmentand hydrazine treatment are preferably converted into ruthenium oxide,but the particles formed by the alkali treatment and hydrazine treatmentcan be remained as far as the effect of the present invention is notadversely affected.

The process of oxidizing one treated with the alkali and hydrazine,washing the remained alkali metal chloride, and drying is a preferablepreparation process. It is preferred that the alkali metal chloridecontained on calcination is sufficiently washed with water. The processof measuring the alkali metal chloride after washing includes a processof examining the presence/absence of white turbidity by adding anaqueous silver nitrate solution to the filtrate. However, the alkalimetal chloride may be remained as far as the effect of the presentinvention is not adversely affected.

According to a preferable preparation process, the washed catalyst isthen dried. Regarding the drying conditions, the drying temperature ispreferably from 50 to 200° C. and the drying time is preferably from 1to 10 hours.

The supported ruthenium oxide catalyst produced by the above steps ishighly active, and the activity was higher than that of the catalystprepared by oxidizing a catalyst obtained by reducing ruthenium chloridewith hydrogen. Furthermore, a catalyst obtained by previously treatingruthenium chloride by using an alkali, treating by using hydrazine(alternatively, alkali treatment and hydrazine treatment aresimultaneously conducted), and oxidizing showed higher activity thanthat of a catalyst obtained by treating ruthenium chloride withhydrazine, and oxidizing.

The supported ruthenium oxide catalyst used in the catalyst (3) of thepresent invention, which is obtained by reducing a ruthenium compoundsupported on a carrier with a reducing hydrogenated compound, andoxidizing, is a catalyst containing a supported ruthenium oxide catalystcomprising ruthenium oxide supported on a carrier. In general, it isindustrially used in the form of being supported on a carrier.

As the carrier, the same carriers as those used in the catalysts (1) and(2) of the present invention can be used.

As the weight ratio of the ruthenium oxide to the carrier, the sameratio as that in the catalysts (1) and (2) of the present invention isused.

As the ruthenium compound to be supported on the carrier, for example,the same ruthenium compounds as those used in the catalysts (1) and (2)of the present invention are used.

The process of supporting the ruthenium compound on the carrierincludes, for example, impregnation process and equilibrium adsorptionprocess.

The reducing hydrogenated compound used for reducing the rutheniumcompound supported on the carrier include for example, boron hydridecompound such as NaBH₄, Na₂B₂H₆, Na₂B₄H₁₀, Na₂B₅H₉, LiBH₄, K₂B₂H₆,K₃B₄H₁₀, K₂B₅H₉ and Al(BH₄)₃; organometallic boron hydride compound suchas LiB[CH(CH₃)C₂H₅]₃H, LiB(C₂H₅)₃H, KB[CH(CH₃)C₂H₅]₃H andKB[CH(CH₃)CH(CH₃)₂]₃H; metal hydride such as LiAlH, NaH, LiH and KH; andorganometallic hydride such as [(CH₃)₂CHCH₂]₂AlH. Preferable reducingagents are alkali metal boron hydride compound such as NaBH₄, Na₂B₂H₆,Na₂B₄H₁₀, Na₂B₅H₉, LiBH₄, K₂B₂H₆, K₃B₄H₁₀ and K₂B₅H₉. More preferableone is NaBH₄.

Preferred embodiment of the process of preparing the supported rutheniumoxide catalyst used in the catalyst (3) of the present invention includea preparation process comprising the following steps:

a ruthenium compound supporting step: step of supporting a rutheniumcompound on a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium compoundsupporting step by using a reducing hydrogenated compound; and

an oxidizing step: step of oxidizing one obtained in the reducing step;or

a ruthenium compound supporting step: step of supporting a rutheniumcompound on a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium compoundsupporting step by using a reducing hydrogenated compound;

an alkali metal chloride adding step: step of adding an alkali metalchloride to one obtained in the reducing step; and

an oxidizing step: step of oxidizing one obtained in the alkali metalchloride adding step.

More preferred embodiment of the process of preparing the supportedruthenium oxide catalyst used in the catalyst (3) of the presentinvention include a preparation process comprising the following steps:

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium hydridesupporting step by using an alkali metal boron halide compound; and

an oxidizing step: step of oxidizing one obtained in the reducingcompound treating step; or

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium halidesupporting step by using an alkali metal boron hydride compound;

an alkali metal chloride adding step: step of adding an alkali metalchloride to one obtained in the reducing step; and

an oxidizing step: step of oxidizing one obtained in the alkali metalchloride adding step.

More preferred embodiment of the process of preparing the supportedruthenium oxide catalyst used in the catalyst (3) of the presentinvention include a preparation process comprising the following steps:

a ruthenium chloride supporting step: step of supporting rutheniumchloride on a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium chloridesupporting step by using sodium boron hydride; and

an oxidizing step: step of oxidizing one obtained in the reducing step;or

a ruthenium chloride supporting step: step of supporting rutheniumchloride on a carrier of a catalyst;

a reducing step: step of reducing one obtained in the ruthenium chloridesupporting step by using sodium boron hydride;

an alkali metal chloride adding step: step of adding an alkali metalchloride to one obtained in the reducing step; and

an oxidizing step: step of oxidizing one obtained in the alkali metalchloride adding step.

The respective steps will be explained below.

The ruthenium chloride supporting step is a step of supporting rutheniumchloride on a carrier of a catalyst. The amount of ruthenium chlorideused in the ruthenium chloride supporting step is usually an amountcorresponding to a preferable weight ratio of ruthenium oxide to thecarrier. That is, a solution of ruthenium chloride is supported on thealready listed carrier of the catalyst. As the solvent, for example,water and an organic solvent such as alcohol are used, and water ispreferred. A ruthenium compound other than ruthenium chloride can alsobe used. However, when using a compound which does not dissolve inwater, there can be used an organic solvent capable of dissolving it,for example, hexane and tetrahydrofuran. Then, supported one can bedried or reduced without being dried, but a process of drying ispreferred. Regarding the conditions for drying the supported one, thedrying temperature is preferably from 50 to 200° C. and the drying timeis preferably from 1 to 10 hours.

The reducing step is a step of reducing one obtained in the rutheniumchloride supporting step by using sodium boron hydride (NaBH₄). Theprocess of the reducing step includes a process of dipping one obtainedin the ruthenium chloride supporting step in a solution of sodium boronhydride. The sodium boron hydride solution includes aqueous solution andsolution of an organic solvent such as alcohol, but a mixed solution ofwater and an organic solvent can also be used. Preferably, a mixedsolution of water and alcohol is used and, more preferably, a solutionof water and ethanol is used. The concentration of the solution ofsodium boron hydride is usually from 0.05 to 20% by weight, andpreferably from 0.1 to 10% by weight. The molar ratio of the sodiumboron hydride to the supported ruthenium is usually from 1.0 to 30, andpreferably from 2.0 to 15. The catalyst may be washed with water afterreducing, or may be subjected to a step of washing with an aqueousalkali metal chloride solution as an operation of the alkali metalchloride adding step. Preferably, a process of reducing, washing withwater, and drying is adopted.

It is also possible to reduce with a reducing compound other then sodiumboron hydride. In that case, an aprotic anhydrous solvent is preferablyused. For example, a supported ruthenium compound is reduced with areducing hydrogenated compound other than sodium boron halide by using atoluene solvent.

The alkali metal chloride adding step is a step of adding an alkalimetal chloride to one obtained in the reducing step. This step isconducted in the same manner as that in the alkali metal chloride addingstep conducted in the catalysts (1) and (2) of the present invention.

The oxidizing step is a step of oxidizing one obtained in the reducingstep (in the case of using no alkali metal chloride adding step), or astep of oxidizing one obtained in the alkali metal chloride adding step(in the case of using the alkali metal chloride adding step). This stepis conducted in the same manner as that in the oxidizing step conductedin the catalysts (1) and (2) of the present invention.

By the calcination, the metal ruthenium supported on the carrier isconverted into a supported ruthenium oxide catalyst. It can be confirmedby analysis such as X-ray diffraction and XPS (X-ray photoelectronspectroscopy) that the metal ruthenium was converted into rutheniumoxide. Incidentally, substantially total amount of the metal rutheniumis preferably converted into ruthenium oxide, but the metal rutheniumcan be remained as far as the effect of the present invention is notadversely affected.

The process of oxidizing the supported metal ruthenium, washing theremained alkali metal chloride with water, and drying is a preferablepreparation process. It is preferred that the alkali metal chloridecontained on calcination is sufficiently washed with water. The processof measuring the alkali metal chloride after washing includes a processof examining the presence/absence of white turbidity by adding anaqueous silver nitrate solution to the filtrate. However, the alkalimetal chloride may be remained as far as the effect of the presentinvention is not adversely affected.

The washed catalyst is preferably then dried. Regarding the dryingconditions, the drying temperature is preferably from 50 to 200° C. andthe drying time is preferably from 1 to 10 hours.

The supported ruthenium oxide catalyst produced by the above steps ishighly active, and is very effective for a process for preparingchlorine by oxidizing hydrogen chloride with oxygen.

The supported ruthenium oxide catalyst used in the catalyst (4) of thepresent invention is a supported ruthenium oxide catalyst using titaniumoxide containing rutile titanium oxide as a carrier. As the titaniumoxide, for example, rutile titanium oxide, anatase titanium oxide andnon-crystal titanium oxide are known. The titanium oxide containingrutile titanium oxide used in the present invention refers to onecontaining a rutile crystal, wherein a ratio of the rutile crystal tothe anatase crystal in the titanium oxide is measured by X-raydiffraction analysis. The measuring process will be described in detailhereinafter. When the chemical composition of the carrier used in thepresent invention is composed of titanium oxide alone, the proportion ofthe rutile crystal is determined from a ratio of the rutile crystal tothe anatase crystal in the titanium oxide by using X-ray diffractionanalysis. In the present invention, a mixed oxide of the titanium oxideand other metal oxide is also used. In that case, the proportion of therutile crystal is determined by the following process. The oxide to bemixed with the titanium oxide includes oxides of elements, and preferredexamples thereof include alumina, zirconium oxide and silica. Theproportion of the rutile crystal in the mixed oxide is also determinedfrom the ratio of the rutile crystal to the anatase crystal in thetitanium oxide by using X-ray diffraction analysis. It is necessary tocontain the rutile crystal. In this case, the content of the oxide otherthan the titanium oxide in the mixed oxide is within a range from 0 to60%by weight. Preferred carrier includes titanium oxide which does notcontain a metal oxide other than titanium oxide.

It is necessary that the titanium oxide contains the rutile crystal. Theproportion of the rutile crystal is preferably not less than 10%, morepreferably not less than 30%, and most preferably not less than 80%.

The process for preparing the titanium oxide containing the rutilecrystal includes various processes. In general, the following processesare exemplified. For example, when using titanium tetrachloride as a rawmaterial, titanium tetrachloride is dissolved by adding dropwise inice-cooled water, and then neutralized with an aqueous ammonia solutionto form titanium hydroxide (ortho-titanic acid). Thereafter, the formedprecipitate was washed with water to remove a chlorine ion. In thatcase, when the temperature on neutralization becomes higher than 20° C.or the chlorine ion is remained in the titanium oxide after washing,conversion into a stable rutile crystal is liable to occur oncalcination. When the calcination temperature becomes not less than 600°C., conversion into rutile occurs (Catalyst Preparation Chemistry, 1989,page 211, Kodansha). For example, a reaction gas is prepared by passingan oxygen-nitrogen mixed gas through a titanium tetrachloride evaporatorand the reaction gas is introduced into areactor. The reaction betweentitanium tetrachloride and oxygen starts at a temperature of about 400°C. and titanium dioxide formed by the reaction of a TiCl₄—O₂ system ismainly an anatase type. However, when the reaction temperature becomesnot less than 900° C., formation of a rutile type can be observed(Catalyst Preparation Chemistry, 1989, page 89, Kodansha). Thepreparation process includes, for example, a process of hydrolyzingtitanium tetrachloride in the presence of ammonium sulfate and calcining(e.g. Shokubai Kougaku Kouza 10, Catalyst Handbook by Element, 1978,page 254, Chijin Shokan) and a process of calcining an anatase titaniumoxide (e.g. Metal Oxide and Mixed Oxide, 1980, page 107, Kodansha).Furthermore, rutile titanium oxide can be obtained by a process forhydrolyzing an aqueous solution of titanium tetrachloride by heating.Rutile titanium oxide is also formed by previously mixing an aqueoustitanium compound solution of titanium sulfate or titanium chloride witha rutile titanium oxide powder, hydrolyzing the mixture by heating orusing an alkali, and calcining at low temperature of about 500° C.

The process of determining the proportion of the rutile crystal in thetitanium oxide includes a X-ray diffraction analysis and, as a X-raysource, various X-ray sources can be used. For example, a K α ray ofcopper is used. When using the K α ray of copper, the proportion of therutile crystal and the proportion of the anatase are respectivelydetermined by using an intensity of a diffraction peak of 2θ=27.5 degreeof the plane (110) and an intensity of a diffraction peak of 2θ=25.3degree of the plane (101). The carrier used in the present invention isone having a peak intensity of the rutile crystal and a peak intensityof the anatase crystal, or one having a peak intensity of the rutilecrystal. That is, the carrier has both of a diffraction peak intensityof the rutile crystal and a diffraction peak of the anatase crystal, orhas only a diffraction peak of the rutile crystal. Preferred carrier isone wherein a proportion of the peak intensity of the rutile crystal tothe total of the peak intensity of the rutile crystal and the peakintensity of the anatase crystal is not less than 10%. Also in thesupported ruthenium oxide catalyst using in the titanium oxide carriercontaining rutile titanium oxide, an amount of an OH group contained inthe carrier is preferably a similar amount to the catalyst (5) of thepresent invention. Although the details will be described with regard asthe catalyst (5) of the present invention, the amount of the OH group ofthe titanium oxide of the carrier used in the catalyst is usually from0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier), preferably from 0.2×10⁻⁴ to 20×10⁻⁴(mol/g-carrier), and more preferably from 3.0×10⁻⁴ to 15×10⁻⁴(mol/g-carrier).

The supported ruthenium oxide catalyst used in the catalyst (5) of thepresent invention is a supported ruthenium oxide catalyst obtained bythe steps which comprises supporting a ruthenium compound on a carrier,treating the supported one by using reducing compound or reducing agentin a liquid phase, and oxidizing the resulted one, wherein titaniumoxide containing an OH group in an amount of 0.1×10⁻⁴ to 30×10⁻⁴(mol/g-carrier) per unit weight of a carrier is used as the carrier. Thecarrier includes, for example, rutile crystal carrier, anatase crystalcarrier and non-crystal carrier. Preferable carriers are rutile crystalcarrier and anatase crystal carrier, and more preferable one is rutilecrystal carrier. It is generally known that a hydroxyl group representedby OH, bound to Ti, exists on the surface of the titanium oxide. Thetitanium oxide used in the present invention is one containing an OHgroup, and the process of measuring the content of OH group will bedescribed in detail hereinafter. When the chemical composition of thecarrier used in the present invention is consisting essentially oftitanium oxide alone, it is determined from the content of the OH groupin the titanium oxide. In the present invention, a mixed oxide of thetitanium oxide and other metal oxide is also used. The oxide to be mixedwith the titanium oxide includes oxides of elements, and preferredexamples thereof include alumina, zirconium oxide and silica. In thatcase, the content of the oxide other than the titanium oxide in themixed oxide is within a range from 0 to 60% by weight. Also this case,the content of the OH group per unit weight of the carrier contained inthe carrier is determined by the measuring process which is alsodescribed in detail hereinafter. Preferred carrier is titanium oxidewhich does not contain the metal oxide other than the titanium oxide.

When the content of the OH group of the carrier is large, the carrierand supported ruthenium oxide may react each other, resulting indeactivation. On the other hand, when the content of the OH group of thecarrier is small, the activity of the catalyst is lowered sometimes bysintering of the supported ruthenium oxide and the other phenomenon

The process of determining the content of the OH group of the titaniumoxide includes various processes. For example, a process using athermogravimetric process (TG) is exemplified. When using thethermogravimetric process, the temperature is kept constant and, afterremoving excess water in a sample, the sample is heated and the contentof the OH group is measured from a weight loss. According to thisprocess, the amount of the sample is small and it is difficult tomeasure with good accuracy. When heat decomposable impurities exist inthe carrier, there is a drawback that the actual content of the OH groupis not determined. When using the measurement of ignition loss (Igloss)for measuring the content of the OH group from the weight loss of thesample in the same manner, the measurement with high accuracy can beconducted if the amount of the sample is increased. However, aninfluence of the heat decomposable impurities is exerted similar to thecase of the thermogravimetric process. Furthermore, there is also adrawback that the weight loss obtained by the thermogravimetric processand ignition loss measurement also includes the bulk OH group contentwhich is not effective on preparation of the catalyst.

A process using sodium naphthalene is also exemplified. According tothis process, an OH group in a sample is reacted with sodium naphthaleneas a reagent and then the content of the OH group is measured from thetitration amount of sodium naphthalene. In this case, since a change inconcentration of the reagent for titration and a trace amount of waterexert a large influence on the results, the measuring results areinfluenced by the storage state of the reagent. Therefore, it is verydifficult to obtain a value with good accuracy.

A titration process using an alkyl alkali metal is also exemplified. Thetitration process using the alkyl alkali metal includes a preferableprocess of suspending a titanium oxide carrier or a titanium oxidecarrier powder in a dehydrated solvent, adding dropwise an alkyl alkalimetal in a nitrogen atmosphere, and determining the amount of the OHgroup contained in the titanium oxide from the amount of hydrocarbongenerated. In that case, since an alkyl alkali metal and water containedin the dehydrated solvent react each other to generate hydrocarbon, thecontent of the OH group in the titanium oxide must be determined bysubtracting the generated amount from the measured value.

Most preferred process includes a process of suspending a titanium oxidecarrier or a titanium oxide carrier powder in a dehydrated solvent,adding dropwise methyl lithium in a nitrogen atmosphere, and determiningthe amount of the OH group contained in the titanium oxide from theamount of hydrocarbon generated, and the content of the OH group in thetitanium oxide catalyst which is used in the claims of the presentinvention is a value obtained by this process.

The measuring procedure includes, for example, the following process.First, a sample is previously dried in an air atmosphere at 150° C. for2 hours and then cooled in a desiccator. Thereafter, a predeterminedamount of the sample is transferred in a flask whose atmosphere wasreplaced by nitrogen, and then suspended in an organic solvent such asdehydrated toluene. The flask is ice-cooled to inhibit heat generationand, after adding dropwise methyl lithium from a dropping funnel, thegenerated gas is collected and the volume at the measuring temperatureis measured. The content of the OH group thus determined, which is usedin the catalyst, is usually from 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier),preferably from 0.2×10⁻⁴ to 20×10⁻⁴ (mol/g-carrier), and more preferablyfrom 3.0×10⁻⁴ to 15×10⁻⁴ (mol/g-carrier).

The process of adjusting the amount of the OH group contained in thetitanium oxide carrier to a predetermined amount includes variousprocesses. For example, a calcination temperature and a calcination timeof the carrier are used for adjusting the OH group of the carrier. TheOH group in the titanium oxide carrier is eliminated by heating, and thecontent of the OH group can be controlled by changing the calcinationtemperature and calcination time. The calcination temperature of thecarrier is usually from 100 to 1000° C., and preferably from 150 to 800°C. The calcination time of the carrier is usually from 30 minutes to 12hours. In this case, it is necessary to pay attention to the point thatthe surface area of the carrier decreases with the increase of thecalcination temperature or the calcination time. When the titanium oxideis produced from a gas phase, one having small content of the OH groupcan be produced. Furthermore, when the titanium oxide is produced froman aqueous phase such as aqueous solution, one having large content ofthe OH group can be produced. Furthermore, a process of treating the OHgroup of the carrier by using an alkali and a process of reacting the OHgroup by using 1,1,1-3,3,3-hexamethyldisilazane are exemplified.

The present invention relates to a process for producing chlorine byusing the above supported ruthenium oxide catalyst supported on thecarrier. A weight ratio of ruthenium oxide to the carrier is usuallywithin a range from 0.1/99.9 to 20.0/80.0, preferably from 0.5/99.5 to15.0/85.0, and morepreferably from 1.0/99.0 to 15.0/85.0. When the ratioof ruthenium oxide is too low, the activity is lowered sometimes. On theother hand, when the ratio of ruthenium oxide is too high, the price ofthe catalyst becomes high sometimes. Examples of the ruthenium oxide tobe supported include ruthenium dioxide, ruthenium hydroxide and thelike.

The process for preparing the supported ruthenium oxide catalyst byusing the above carrier is a process comprising the steps of supportinga ruthenium compound on a carrier, treating the supported one by using areducing compound or a reducing agent in a liquid phase, and oxidizing,and the step of treating with a reducing compound or a reducing agent ina liquid phase includes, for example, a process of treating with areducing compound or a reducing agent in a liquid phase which isconducted in the catalysts (1), (2) and (3) of the present invention,and the process described below. That is, the process includes a processof suspending one comprising the already described ruthenium compoundsupported on the carrier in an aqueous phase or an organic solvent, andbubbling hydrogen, a process of treating by using an organolithiumcompound such as butyl lithium, or an organosodium compound or anorganopotassium compound in an organic solvent, a process of treating byusing an organoaluminum compound such as trialkyl aluminum, and aprocess of treating by using an organomagnesium compound such asGrignard reagent. Furthermore, various organometallic compounds can beused and examples thereof include alkali metal alkoxide such as sodiummethoxide; alkali metal naphthalene compound such as sodium naphthalene;azide compound such as sodium azide; alkali metal amide compound such assodium amide; organocalcium compound; organozinc compound;organoaluminum alkoxide such as alkyl aluminum alkoxide; organotincompound; organocopper compound; organoboron compound; boranes such asborane and diborane; sodium ammonia solution; and carbon monoxide.Various organic compound can also be used and examples thereof includediazomethane, hydroquinone and oxalic acid.

In a process for producing chlorine by oxidizing hydrogen chloride withoxygen, it is preferable that the catalyst (1), (2) or (3) is asupported ruthenium oxide catalyst obtained by using titanium oxidecontaining not less than 10% by weight of rutile titanium oxide as acarrier.

It is more preferable that the catalyst (1), (2) or (3) is a supportedruthenium oxide catalyst obtained by using titanium oxide containing notless than 30% by weight of rutile titanium oxide as a carrier.

It is preferable that the catalyst (4) or (5) is a supported rutheniumoxide catalyst obtained by supporting a ruthenium compound on a carrier,reducing the supported one by using a reducing hydrogenated compound,and oxidizing.

It is preferable that the catalyst (4) or (5) is a supported rutheniumoxide catalyst obtained by supporting a ruthenium compound on a carrier,treating the supported one by using a reducing compound, and oxidizing.

It is preferable that the catalyst (4) or (5) is a supported rutheniumoxide catalyst obtained by supporting a ruthenium compound on a carrier,treating the supported one by using an alkali solution of a reducingcompound, and oxidizing.

Next, catalyst system will be explained bellow. The catalyst system (6)in the present invention is a catalyst system containing at least thefollowing component (A) and (B), wherein the content of the component(B) in the catalyst system is not less than 10% by weight:

(A) an active component of catalyst; and

(B) a compound component wherein thermal conductivity of a solid phasemeasured by at least one point within a range from 200 to 500° C. is notless than 4 W/m. ° C.;

The catalyst system in the present invention means any packing solidcapable of forming a catalyst bed layer. For example, the catalystincludes not only particles containing an active component of thecatalyst, but also particles of an inactive component containing nocatalytic active component. The catalyst bed layer includes fixed bedand fluidized bed.

The catalyst in the present invention means a molding and a powder whichcontain a catalytic active component and doesn't mean an inactivemolding and an inactive powder included in a catalyst bed.

As the above active component of the catalyst as the component (A) inthe present invention, for example, copper, chromium, ruthenium, and acompound thereof are known.

The content of the component (A) in the catalyst is preferably from 0.1to 90% by weight, and more preferably from 0.2 to 80% by weight. Whenthe content of the component (A) is too small, the activity of thecatalyst may be lowered. On the other hand, when the content of thecomponent (A) is too large, the cost of the catalyst may become high.

The example of the above active component of catalyst (A) includeruthenium compound. When using a ruthenium compound, a catalyst havinghigh activity can be prepared, so the ruthenium compound is preferable.The more preferable example include ruthenium oxide. A catalyst havinghigher activity can be prepared by using ruthenium oxide.

In the view of the catalyst activity, it is preferable that a component(A) is a component supported on the catalyst carrier component or acomponent (B). For example, in the case of a component (A) is anexpensive noble metal compound such as ruthenium, large effects can berealized in the cost of the catalyst by supporting a component (A) onthe catalyst carrier component or the component (B) because the catalystactivity increases by supporting a small amount of noble metal.

More preferable example includes supported ruthenium oxide catalyst onthe catalyst carrier component or the component (B).

The component (B) in the present invention is a compound wherein thermalconductivity of a solid phase measured by at least one point within arange from 200 to 500° C. is not less than 4 W/m. ° C.

The thermal conductivity of compounds of the solid phase in the presentinvention means the thermal conductivity measured in the state ofcontinuum (continuous phase) such as a crystal, an amorphous solid, aglass. For example, in the case of the compound is a crystal, thermalconductivity is measured in the phase of crystal solid.

The thermal conductivity of the solid phase is described, for example,in Latest Oxide Handbook-Physiochemical Properties-, (published byMoscow Metallurgical Publication, 1978), Thermophysical PROPERTIES ofHigh Temperature Solid Metals (Oxides and Their Solutions and Mixtures)(published by The Macmillan Company, 1967).

The thermal conductivity of the solid phase is preferably higher. It isnecessary not less than 4 W/m. ° C. And it is further preferably notless than 15 W/m. ° C.

Preferred example of the component (B) includes α-alumina, rutile tindioxide, rutile titanium oxide, silicon nitride and silicon carbide.More preferred one is α-alumina. When an inactive component is added,the activity of the catalyst is sometimes lowered. However, by selectingan additive capable of improving the thermal conductibility withmaintaining the activity of the catalyst, the reaction can be conductedin more industrially advantageous manner. Since the thermalconductibility can be improved with maintaining the activity of thecatalyst by adding α-alumina, preferred example of the component (B) inview of the activity of the catalyst includes α-alumina.

It is necessary the content of the component (B) is not less than 10% byweight, and preferably not less than 20% by weight.

By using a catalyst containing not less than 10% by weight of thecomponent (B), the reaction heat is sufficiently removed, thereby makingit easy to control the reaction temperature. Since the whole catalystbed can be utilized at the temperature capable of oxidizing hydrogenchloride at an industrially sufficient reaction rate, high reactionconversion can be realized.

The catalyst carrier component in the present invention is as follows.The examples thereof include oxides and mixed oxides of elements, suchas titanium oxide, alumina, zirconium oxide, silica, titanium mixedoxide, zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxideand the like. Titanium oxide is the most preferable catalyst carriercomponent among the above example because the catalyst has highcatalytic activity by using a ruthenium compound as an active componentof catalyst (A)

When a catalyst carrier component is a compound wherein thermalconductivity of a solid phase measured by at least one point with in arange from 200 to 500° C. is not less than 4 W/m. ° C., the abovecatalyst carrier component is regarded as a component (B). For example,in the case of titanium oxide, there exists rutil crystal titaniumoxide, anatase crystal titanium oxide, etc. As thermal conductivity ofrutil titanium oxide of a solid phase measured at 200° C. is 7.5 W/m. °C., rutil titanium oxide is regarded as a component (B). And in the caseof alumina, there exists α-alumina, γ-alumina, etc. As thermalconductivity of α-alumina of a solid phase measured at 200° C. is 23W/m. ° C., α-alumina is regarded as a component (B). As rutil titaniumoxide, α-alumina, etc wherein thermal conductivity of the catalystcarrier component is not less than 4 W/m. ° C. at 200° C. in the solidphase, they are regarded as a component (B). However, as the thermalconductivity of zirconium oxide of a solid phase measured at 400° C. is2.05 W/m. ° C., zirconium oxide is not regarded as a component (B).Therefore the catalyst carrier component includes a part of component(B). On the contrary, for example, in the case of silicon nitride, thethermal conductivity of a solid phase measured at 200° C. is 24 W/m. °C., so it is regarded as a component (B), but it is not regarded as acatalyst carrier component because silicon nitride has too small surfacearea to support an active component of catalyst (A). Therefor, among thecomponent (B), the component which can't support an active component (A)is not a catalyst carrier component. As mentioned above, the catalystcarrier component include a part of component (B).

The catalyst system in the present invention contains not less than 10%by weight of a component (B) because the thermal conductibility improveby containing the componennt (B). The catalyst system preferablycontains not less than 20% by weight of a component (B) because thethermal conductibility can be much improved.

Examples of the shape of the carrier of the catalyst in the case ofsupporting the active component of the catalyst includes powder, sphere,column, extruded shape and those obtained by spray drying process. Inthe case of the powder, a process of using the powder after molding intosphere, column, extruded shape and the like is generally used so as touse the powder industrially.

Next the catalyst system which contains the component (B) in the presentinvention will be explained. The catalyst system comprises twocomponents such as the component (A) and the component (B), or comprisesthree components such as the component (A), the component (B) and thecatalyst carrier component. And the catalyst system can contain theother component such as an inorganic binder which is used for a moldingaid.

First embodiment includes a process of using a catalyst made of amolding containing the components (A) and (B) obtained by integrallymolding. For example, the catalyst preparation includes the steps whichcomprises mixing an active component of catalyst (A) with component (B),molding the components by using an inorganic binder, and calcining. Theresulting catalyst is preferable catalyst being easily charged in areactor because of integrally molding.

The process of using a catalyst made of a molding containing thecomponent (A), the component (B) and catalyst carrier component obtainedby integrally molding is exemplified. For example, the catalystpreparation method includes the steps which comprises mixing an activecomponent (A) with fine particle of catalyst carrier component resultedin high surface area catalyst, mixing the resulted one with component(B), molding the component by using inorganic binder, and calcining. Theresulting catalyst is preferable as the catalyst is molded integrallyand the catalytic activity is improved.

The catalyst made of a molding containing the component (A) supported ona component (B) is exemplified. The catalyst preparation method includethe steps which comprises supporting a component (A) on a component (B)which have high surface area, wherein a supported one has high catalyticactivity , molding the resulted one by using inorganic binder, andcalcining. The resulting catalyst is preferable as the catalyst has highactivity, good thermal conductibility, and easily charges into a reactorbecause of integrally molding.

The catalyst made of a molding containing a component (A) supported on acatalyst carrier component and component (B) is exemplified. Thecatalyst preparation method includes the steps which comprisessupporting a component (A) on a catalyst carrier component having highsurface area, mixing the resulted one with component (B), molding themixed one by using inorganic binder integrally, and calcining. Theresulting catalyst is more preferable as the catalyst has high catalyticactivity, good thermal conductibility.

The catalyst made of a molding containing a component (A) supported on amixture of a catalyst carrier component with a component (B) isexemplified. The catalyst preparation method includes the steps whichcomprises mixing catalyst carrier component with a component (B),molding the resulted one by using inorganic binder integrally, calciningthe molded one, and supporting a component (A) on the calcined one. Theresulting catalyst is more preferable as the catalyst has high catalyticactivity, good thermal conductibility.

A second embodiment includes a process using a catalyst systemcomprising both of a molding containing the component (A) and (B)obtained by integrally molding and a molding containing the component(B) obtained by integrally molding. For example, the catalyst system isa mixture of the two moldings. The preparation method of one molding ofthe catalyst includes the steps which comprises mixing a component (A)with a component (B), molding the components by using inorganic binderintegrally, calcining. The preparation method of another moldingincludes the steps which comprises molding the component (B) by usinginorganic binder integrally, calcining. The resulting catalyst system ispreferable as the catalyst system shows good thermal conductibility. Themolding containing a component (A) and a component (B) integrally isexemplified in the first embodiment.

The method includes a process of using a catalyst system comprising bothof a molding containing a component (A) and catalyst carrier componentobtained by integrally molding and a molding containing a component (B)obtained by integrally molding. One example of the catalyst system is amixture of the two moldings. The preparation method of one molding ofthe catalyst includes the steps which comprises supporting a component(A) on a catalyst carrier component, molding the supported one by usinginorganic binder integrally, calcining. The preparation of anothermolding include the steps which comprises molding a component (B) byusing inorganic binder integrally, calcining. The another example of thecatalyst system is a mixture of the two moldings. The preparation methodof one molding of the catalyst includes the steps which comprisesmolding a catalyst carrier component by using inorganic binderintegrally, calcining the molded one, supporting a component on thecalcined one. The preparation method of another one includes the stepswhich comprises molding a component (B) by using inorganic binderintegrally, calcining. The two examples of the catalyst systems arepreferable examples respectively as the catalyst systems show highcatalytic activity, and good thermal conductibility. Generally thecatalyst system obtained by mixing the sphere molding of α-alumina withthe sphere molding which comprises a component (A), a catalyst carriercomponent is more preferable as the catalyst system has good thermalconductibility.

Among the above catalysts, a preferable one is a catalyst which thecomponent (C) is α-alumina.

Among the above catalysts, preferable one is a catalyst which thecomponent (A) is a component containing ruthenium. More preferable oneis a catalyst which the component (A) is ruthenium oxide.

Among the above catalysts, preferable one is a catalyst which thecarrier of the catalyst is titanium oxide.

The catalyst used in the present invention is a catalyst capable ofproducing chlorine by oxidizing hydrogen chloride with oxygen.Preferable catalyst includes, for example, catalyst containing copper asan active component of the catalyst, such as Deacon catalyst; catalystcontaining chromium as an active component of the catalyst, such aschromia-silica catalyst; and catalyst containing ruthenium as an activecomponent of the catalyst. More preferable catalyst is a catalystcontaining ruthenium. Since ruthenium is expensive, a catalystcontaining a supported ruthenium catalyst supported on the carrier ofthe catalyst is a more preferable catalyst.

The supported ruthenium catalyst includes, for example, supportedruthenium oxide catalyst, supported metal ruthenium catalyst, andcatalyst obtained by supporting a ruthenium compound.

As the supported ruthenium catalyst, a supported ruthenium oxidecatalyst is preferred because high activity can be obtained by low Rucontent. The carrier of the supported ruthenium catalyst includes oxidesand mixed oxides of elements, such as titanium oxide, alumina, zirconiumoxide, silica, titanium mixed oxide, zirconium mixed oxide, aluminummixed oxide, silicon mixed oxide and the like. Preferable catalystcarrier components are titanium oxide, alumina, zirconium oxide andsilica, and more preferable catalyst carrier component is titaniumoxide, and most preferable carrier is titanium oxide having rutilecrystalline structure.

The supported ruthenium oxide catalyst will be explained below. A weightratio of ruthenium oxide to the carrier of the catalyst is usuallywithin a range from 0.1/99.9 to 20.0/80.0, preferably from 0.2/99.8 to15.0/85.0, and more preferably from 0.5/99.5 to 10.0/90.0. When theproportion of the ruthenium oxide is too low, the activity is loweredsometimes. On the other hand, when the proportion of ruthenium oxide istoo high, the price of the catalyst becomes high sometimes. Examples ofthe ruthenium oxide to be supported include ruthenium dioxide, rutheniumhydroxide and the like.

The process of preparing a supported ruthenium oxide will be explainedbelow.

The process of preparing a catalyst includes various processes, and fourkinds of preparation process will be shown as an embodiment. A catalysthaving high thermal conductibility can be used in the present invention,and a process of increasing the thermal conductibility of the catalystincludes a process for preparing a catalyst by mixing a compound havinghigh thermal conductivity. Examples of the component (B) having highthermal conductivity includes various compounds, but a process usingα-alumina is exemplified. The catalyst carrier component includesvarious compounds , but the embodiment using titanium oxide isexemplified. The catalyst is prepared by supporting a ruthenium compoundon the catalyst carrier component but the ruthenium compound to besupported varies depending on the preparation process. Now theembodiment using ruthenium chloride is exemplified.

The first embodiment of four kinds of the preparation processes is aprocess which comprises uniformly mixing a titanium oxide powder with anα-alumina powder, adding a titanium oxide sol, and molding a carrier ofa catalyst. The proportion of the titanium oxide sol to be mixed ispreferably within a range from 3 to 30% by weight in terms of titaniumoxide in the titanium oxide sol, based on the weight of the titaniumoxide and α-alumina. The molding process includes process of moldinginto a spherical shape and a process of extrusion molding. The moldedobject is dried and then calcined under air to prepare a carrier of acatalyst. The calcination temperature is preferably within a range from300 to 800° C. At this stage, a carrier having high thermalconductibility can be obtained. Then, an aqueous solution of rutheniumchloride is supported by impregnation. The amount of ruthenium chlorideto be used corresponds to a preferable ratio of the ruthenium oxide tothe carrier of the catalyst. Then, the supported one is dried. Asupported ruthenium oxide catalyst is prepared by reducing the dried onewith a reducing hydrogenated compound such as sodium boron hydride, andoxidizing, or prepared by treating the dried one with a reducingcompound such as hydrazine, and oxidizing. The preparation process willbe explained in detail hereinafter.

The second embodiment of four kinds of the preparation processes is aprocess which comprises uniformly mixing a titanium oxide powder with anα-alumina powder, and supporting an aqueous ruthenium chloride byimpregnation. The amount of the ruthenium chloride to be usedcorresponds to a preferable ratio of the ruthenium oxide to the carrierof the catalyst. Then, the supported one is dried. The dried one isreduced with a reducing hydrogenated compound such as sodium boronhydride or treated with a reducing compound such as hydrazine. Thepreparation process will be explained in detail hereinafter. Then, atitanium oxide sol is added and a carrier of the catalyst is molded. Theproportion of the titanium oxide sol is the same proportion as thatshown in the first embodiment. Then, a catalyst is prepared by dryingthe molded one, calcining under air to oxidize ruthenium, and washingwith water in the same manner as the process of preparing the supportedruthenium oxide catalyst, which will be explained in detail hereinafter.At this stage, a catalyst having good thermal conductibility can beobtained.

The third embodiment of four kinds of the preparation processes is aprocess which comprises supporting an aqueous solution of rutheniumchloride on a powder of titanium oxide by impregnation. The amount ofthe ruthenium chloride to be used corresponds to a preferable ratio ofthe ruthenium oxide to the carrier of the catalyst. Then, the supportedone is dried. The dried one is reduced with a reducing hydrogenatedcompound such as sodium boron hydride or treated with a reducingcompound such as hydrazine. The preparation process will be explained indetail hereinafter. Then, α-alumina is uniformly mixed. Then, a titaniumoxide sol is added and a carrier of the catalyst is molded. Theproportion of the titanium oxide sol is the same proportion as thatshown in the first embodiment. Then, a catalyst is prepared by dryingthe molded one, calcining under air to oxidize ruthenium, and washingwith water in the same manner as the process of preparing the supportedruthenium oxide catalyst, which will be explained in detail hereinafter.At this stage, a catalyst having good thermal conductibility can beobtained.

The fourth embodiment of four kinds of the preparation processes is aprocess which comprises supporting an aqueous solution of rutheniumchloride on a powder of titanium oxide by impregnation. The amount ofthe ruthenium chloride to be used corresponds to a preferable ratio ofthe ruthenium oxide to the carrier of the catalyst. Then, the supportedone is dried. The dried one is reduced with a reducing hydrogenatedcompound such as sodium boron hydride and then oxidized to prepare asupported ruthenium oxide catalyst. Alternatively, the dried one istreated with a reducing compound such as hydazine and then oxidized toprepare a supported ruthenium oxide catalyst. The preparation processwill be explained in detail hereinafter. Then, α-alumina is uniformlymixed. Then, a titanium oxide sol is added and a carrier of the catalystis molded. The proportion of the titanium oxide sol is the sameproportion as that shown in the first embodiment. Then, the molded oneis dried and then calcined under air. The calcination temperature ispreferably within a range from 300 to 600° C. Then, the calcined one iswashed with water to prepare a catalyst. At this stage, a catalysthaving good thermal conductibility can be obtained.

The process for preparing a supported ruthenium oxide catalyst used inthe present invention includes a process for preparing a supportedruthenium oxide catalyst by supporting a ruthenium compound on a carrierof a catalyst, reducing the supported one by using a reducinghydrogenated compound such as sodium boron hydride, and oxidizing, or aprocess for preparing a supported ruthenium oxide catalyst by treating aruthenium compound by using a reducing compound such as hydrazine, andoxidizing, for example, processes for preparing the catalysts (1), (2)and (3) of the present invention.

The first embodiment of the process for preparing a supported rutheniumoxide catalyst used in the present invention includes a process forpreparing a supported ruthenium oxide catalyst by reducing a rutheniumcompound supported on a carrier of a catalyst by using a reducinghydrogenated compound, and oxidizing.

The ruthenium compound to be supported on the carrier of the catalystincludes the same compounds as those listed with respect to thecatalysts (1), (2) and (3) of the present invention.

The reducing hydrogenated compound used for reducing the rutheniumcompound supported on the carrier of the catalyst includes the samecompounds as those listed with respect to the catalyst (3) of thepresent invention.

The second embodiment of the process for preparing a supported rutheniumoxide catalyst used in the present invention includes a process forpreparing a supported ruthenium oxide catalyst by reducing a rutheniumcompound supported on a carrier of a catalyst by using a reducingcompound, and oxidizing.

The ruthenium compound to be supported on the carrier of the catalystincludes the same compounds as those listed with respect to thecatalysts (1), (2) and (3) of the present invention.

The reducing compound used for treating the ruthenium compound supportedon the carrier of the catalyst includes the same compounds as thoselisted with respect to the catalysts (1) and (2) of the presentinvention.

The process for preparing a supported metal ruthenium catalyst will beexplained below. The first embodiment of the process for preparing thesupported ruthenium oxide catalyst was mentioned after the fourembodiment of the process for preparing the catalyst having good thermalconductibility.

The supported metal ruthenium catalyst includes, for example, supportedmetal ruthenium catalyst obtained by supporting a ruthenium compoundshown in the first embodiment of the process for preparing the supportedruthenium oxide on the above-described carrier in the same manner, andreducing the supported one to form metal ruthenium by using a reducingagent, for example, a reducing hydrogenated compound such as sodiumboron hydrate shown in the first embodiment of the process for preparingthe supported ruthenium oxide catalyst, and supported metal rutheniumcatalyst obtained by supporting ruthenium chloride on theabove-described carrier, forming a ruthenium hydroxide on the carrier byalkali hydrolysis, and reducing the ruthenium hydroxide by usinghydrogen, but a commercially available Ru catalyst may also be used. Aratio of the metal ruthenium to the carrier in the metal rutheniumsupported on the carrier is usually from 0.1/99.9 to 20/80, andpreferably from 1/99 to 10/90. When the amount of the metal ruthenium istoo small, the activity of the catalyst is lowered. On the other hand,when the amount of the metal ruthenium oxide is too large, the price ofthe catalyst becomes high.

The process for preparing a catalyst comprising a supported rutheniumcompound will be explained.

The catalyst comprising a supported ruthenium compound includes the samecompounds as those exemplified in the catalysts (1), (2) and (3) of thepresent invention.

The supporting process includes impregnation process, ion exchangeprocess, precipitation supporting process, coprecipitation process andmixing process. Among them, impregnation process and ion exchangeprocess are preferred.

The impregnation process includes, for example, a preparation process ofsuspending a carrier in a solution prepared by dissolving a rutheniumcompound, evaporating a solvent, and drying. The solvent includes water,methanol and organic solvent, etc.

When the drying temperature of the supported catalyst is too high,volatilization of the ruthenium compound occurs and, therefore, thedrying temperature is preferably from 30 to 200° C. under reducedpressure, and is preferably from about 60 to 400° C. under nitrogen.Under air, the drying temperature is generally a temperature at whichthe ruthenium compound is not decomposed by oxidation with oxygen. Thedrying time is preferably from about 30 minutes to 5 hours.

In a catalyst using a catalyst containing a molding obtained byintegrally molding (A) an active component of catalyst and a catalystcarrier component, and (B) a compound wherein thermal conductivity of asolid phase measured by at least one point within a range from 200 to500° C. is not less than 4 W/m. ° C., the inventors have succeeded inpreparation of a catalyst having almost the same activity of thecatalyst prepared from the component (A) and a catalyst carriercomponent as a catalyst which is obtained by integrally molding threecomponents, a component (A), a catalyst carrier component and acomponent (B).

It is an object of the present invention to obtain chlorine by oxidizinghydrogen chloride with oxygen using the above catalyst system. Whenhydrogen chloride is oxidized with oxygen using the above catalyst, aremoving rate of heat generated during the reaction increases and,therefore, control of the reaction temperature becomes easier and highreaction conversion can be obtained by keeping the whole catalyst bed atsufficient temperature for an industrially desirable reaction rate. Thereaction system for producing chlorine includes, for example, a flowsystem such as fixed bed or fluidized bed, and a gas phase reaction suchas fixed bed flow system and gas phase fluidized bed flow system can bepreferably used. The fixed bed system has an advantage that separationbetween the reaction gas and catalyst is not required and highconversion can be accomplished. In the case of the fixed bed reactor, areaction tube is packed with catalyst particles and, in the case of theexothermic reaction, the reaction tube is cooled from the outside. Insuch a packed bed, since effective thermal conductivity of the particlebed is generally smaller than that of a tube material and that of afluid outside the tube and heat transfer resistance in the particle bedis generally larger than that of a tube material and that of a fluidoutside the tube, the whole heat transfer rate can be markedly improvedby increasing effective thermal conductivity in the particle bed. Theterm “effective thermal conductivity of the particle bed” used hereinmeans a heat transfer rate per unit sectional area of the particle bedin a certain direction per unit length and per unit degree of differencewhich is 1° C. temperature. According to “Thermal Unit Operation, Vol.1” (1976, page 136˜146, Maruzen Co., Ltd.), it is known that effectivethermal conductivity of the particle bed depends on effective thermalconductivity of particles to be packed and thermal conductivity of afluid material existing in the tube, and depends on a fluid velocitywhen the fluid transfers. Among them, effective thermal conductivity ofparticles strongly depends on the thermal conductivity of the solid ofthe component (compound) constituting the particles and, therefore,effective thermal conductivity of the particles and effective thermalconductivity of the particle bed are increased by using the componenthaving large thermal conductivity, and contribute to an improvement inremoving rate of heat generated in the reactor in the exothermicreaction such as oxidation reaction of hydrogen chloride. As describedabove, the effect of the present invention is particularly large whenthe fixed bed system is adopted. The fluidized bed system has anadvantage that heat transfer in the reactor is large and the temperaturedistribution width in the reactor can be minimized. The temperaturedistribution width can be further minimized by using the catalystaccording to the present invention.

By using the catalyst which has good thermal conductibility (heattransfer) and is capable of easily removing heat, the above effect canbe obtained without increasing the heat transfer area per unit volume inthe reactor. For example, comparing a multitube reactors having the samereaction volumes, when the heat transfer area is increased by decreasingthe diameter of the tube, the number of required tubes and amount of therequired material are increased and the price of the reactor becomeshigh. However, when using the catalyst which has good thermalconductibility (heat transfer) and is capable of easily remove heat,control of the reaction temperature can be made easier withoutincreasing the heat transfer area of the reactor and the reactor withcheap price can be used. Therefore, it is industrially advantageous.

The supported ruthenium oxide catalyst containing macropores having apore diameter of 0.03 to 8 micrometer used in the catalyst (7) of thepresent invention is a catalyst containing a supported ruthenium oxidecatalyst comprising ruthenium oxide supported on a carrier. In general,it is industrially used in the form of being supported on the carrier.

The carrier includes oxides and mixed oxides of elements, such astitanium oxide, alumina, zirconium oxide, silica, titanium mixed oxide,zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxide and thelike. Preferable carriers are titanium oxide, alumina, zirconium oxideand silica, and more preferable carrier is titanium oxide. A weightratio of ruthenium oxide to the carrier is usually within a range from0.1/99.9 to 20.0/80.0, preferably from 0.5/99.5 to 15.0/85.0, and morepreferably from 1.0/99.0 to 15.0/85.0. When the proportion of theruthenium oxide is too low, the activity is lowered sometimes. On theother hand, when the proportion of ruthenium oxide is too high, theprice of the catalyst becomes high sometimes. Examples of the rutheniumoxide to be supported include ruthenium dioxide, ruthenium hydroxide andthe like.

The embodiment of the process for preparing the catalyst containingmacropores having a pore diameter of 0.03 to 8 micrometer will bedescribed below. The catalyst is prepared by mixing a carrier powder oftitanium oxide with an organic material for forming pores or aninorganic material for forming pores. First, the case using the organicmaterial for forming pores will be illustrated. The organic material forforming pores includes celluloses such as crystalline cellulose, fibrouscellulose, filter paper and pulp. Fibrous celluloses such as filterpaper and pulp are preferred. After adding water to a carrier powder oftitanium oxide and kneading, the organic material for forming pores suchas cellulose is added and the mixture is sufficiently kneaded. Then,binders such as titania sol, silica sol and alumina sol may also beadded or not. Binders are preferably added. Among sols, titania sol ispreferred. After the sol is added and kneading, the kneaded one isextruded and molded into one having a suitable size using a moldingmachine, such as a extruder. After the molded one is dried, the driedone is calcined to remove the organic material for forming pores such ascellulose. The calcination temperature is preferably from 400 to 700°C., and more preferably from 500 to 600° C. By calcining the carrierunder air, the organic material for forming pores can be removed byburning, thereby to form pores having a pore diameter of 0.03 to 8micrometer in the carrier. A weight ratio of the organic material forforming pores such as cellulose to the carrier powder is usually from1/99 to 40/60, and preferably from 5/95 to 30/70. A weight ratio oftitania, silica and alumina contained in titania sol, silica sol andalumina sol to the carrier powder is usually from 5/95 to 40/60, andpreferably from 10/90 to 30/70.

Then, the case using the inorganic material for forming pores will beillustrated. The inorganic material for forming pores includes alkalimetal salts such as sodium chloride and potassium chloride; alkali metalsulfates such as sodium sulfate and potassium sulfate; and high-meltingpoint inorganic salts such as potassium nitrate. Chlorides of alkalimetals are preferred, and potassium chloride and sodium chloride aremore preferred. After adding water to a carrier powder such as titaniumoxide and kneading, an aqueous solution of the inorganic material forforming pores such as potassium chloride is added and the mixture issufficiently kneaded. Then, binders such as titania sol, silica sol andalumina sol may also be added. Binders are preferably added. Among sols,titania sol is preferred. After the sol is added and kneading, thekneaded one is extruded and molded into one having a suitable size usinga molding machine, for example a extruder. The molded one is dried.After drying, the dried one is sintered by calcining. The calcinationatmosphere includes air and nitrogen, and air is preferred. Thecalcination temperature is preferably from 400 to 700° C., and morepreferably from 500 to 600° C. After cooling to room temperature, theinorganic salt contained in the carrier can be removed by sufficientlywashing the carrier with water. The process of confirming that potassiumchloride and sodium chloride could be removed includes a process ofexamining the presence/absence of white turbidity using an aqueoussilver nitrate solution. By drying the carrier after washing with water,micropores having a diameter of 0.01 to 0.4 micrometer can be formed inthe carrier. A weight ratio of the inorganic material for forming poressuch as inorganic salt to the carrier powder is usually from 5/95 to40/60, and preferably from 5/95 to 30/70. A weight ratio of titania,silica and alumina contained in titania sol, silica sol and alumina solto the carrier powder is usually from 5/95 to 40/60, and preferably from5/95 to 30/70. The carrier having micropores can be prepared in theabove manner.

Among the above-mentioned organic material for forming pores andinorganic material for forming pores organic material for forming poresis preferable.

The embodiment of the process for preparing the supported rutheniumoxide catalyst is as follows. The preparation of the supported rutheniumoxide catalyst containing macropores having a pore diameter of 0.03 to 8micrometer is conducted in the same manner as that in process forpreparing the catalyst, which is conducted in the catalysts (1), (2) and(3) of the present invention using a carrier prepared in the preparationexamples of the already described carrier containing micropores.

The catalyst (7) of the present invention is characterized by using asupported ruthenium oxide catalyst containing macropores having a porediameter of 0.03 to 8 micrometer, and the pore diameter distribution ofmacropores can be measured by a mercury porosimeter. The exist of manypores is preferable. The pore diameter of macropores, which can beformed by the process described above, is usually from 0.03 to 8micrometer, and more preferably from 0.03 to 6 micrometer. The largerpore volume of macropores is preferable. The supported ruthenium oxidecatalyst containing macropores is preferably a catalyst wherein a ratioof an accumulated pore volume of 0.03-6 micrometer to an accumulatedpore volume of 30-200 angstroms is not less than 0.2/1.0, and preferablynot less than 0.29/1.0. Since the pore diameter of the carrier does notchange largely by supporting of the ruthenium compound, the porediameter of the catalyst can be determined by measuring the porediameter of the carrier.

As the catalyst (8) of the present invention, an outer surface-supportedcatalyst obtained by supporting ruthenium oxide on a carrier at theouter surface can also be used. The supported ruthenium oxide catalystused in the present invention is a catalyst wherein the same content asthat of ruthenium oxide described in the item of the supported rutheniumoxide containing macropores is used and the same carrier is preferablyused, that is, a supported ruthenium oxide catalyst obtained bysupporting ruthenium oxide on a carrier. In general, it is industriallyused in the form of being supported on the carrier.

The carrier includes oxides and mixed oxides of elements, such astitanium oxide, alumina, zirconium oxide, silica, titanium mixed oxide,zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxide and thelike. Preferable carriers are titanium oxide, alumina, zirconium oxideand silica, and more preferable carrier is titanium oxide. A weightratio of ruthenium oxide to the carrier is usually within a range from0.1/99.9 to 20.0/80.0, preferably from 0.5/99.5 to 15.0/85.0, and morepreferably from 1.0/99.0 to 15.0/85.0. When the proportion of theruthenium oxide is too low, the activity is lowered sometimes. On theother hand, when the proportion of ruthenium oxide is too high, theprice of the catalyst becomes high sometimes. Examples of the rutheniumoxide to be supported include ruthenium dioxide, ruthenium hydroxide andthe like.

The process of supporting ruthenium oxide on a carrier at the outersurface includes various processes. For example, when a γ-aluminacarrier is impregnated with ruthenium chloride, it is supported at theouter surface and, therefore, it is comparatively easy to prepare acatalyst wherein ruthenium oxide is supported at the outer surface.However, when a carrier such as titanium oxide is impregnated withruthenium chloride, it penetrates into the inside of the carrier and,therefore, it is not easy to support the carrier at the outer surface.Therefore, as the process of supporting ruthenium oxide on a carrier atthe outer surface, various processes have been suggested. For example, aprocess of supporting ruthenium chloride on a carrier by spraying isillustrated. As the process of supporting ruthenium oxide on a carrierof titanium oxide at the outer surface, any known process may be used.The present inventors have found that ruthenium chloride can besatisfactorily supported on a carrier at the outer surface by using analkali preliminary impregnation process described below. The procedurewill be explained by way of the preparation example. That is, first, acarrier of titanium oxide having a suitable particle diameter isimpregnated with an aqueous solution of an alkali metal hydroxide suchas potassium hydroxide and a solution of alkali such as ammoniumcarbonate and ammonium hydrogencarbonate. In this case, a thickness of alayer of ruthenium chloride at the surface to be supported on thecarrier is determined by changing the kind of the alkali, concentrationof the alkali, amount of ruthenium chloride to be supported, and timefrom impregnation with ruthenium chloride to drying. For example, whenusing potassium hydroxide, a thickness of a layer to be impregnated withruthenium chloride can be changed by changing the concentration of theaqueous solution of potassium hydroxide within a range from 0.1 N to 2.0N. Then, the carrier is impregnated with an aqueous solution of analkali, and the carrier is dried. Then, the carrier is impregnated witha solution of ruthenium chloride and the carrier is dried. As thesolution, an aqueous solution, a solution of an organic solvent such asalcohol, or a mixed solution of water and an organic solvent is used,and a solution of an organic solvent such as ethanol is preferred. Then,the carrier impregnated with ruthenium chloride is dried and hydrolyzedby using an alkali to form ruthenium hydroxide, which is converted intoruthenium oxide. Alternatively, the supported ruthenium chloride isreduced to form metal ruthenium, which is oxidized to form rutheniumoxide. The process for preparing the supported ruthenium oxide catalystincludes the following process.

That is, the process of supporting ruthenium chloride on a carrier atthe outer surface was described above, the embodiment of the preparationprocess of converting one supporting ruthenium chloride into a supportedruthenium oxide catalyst is described as follows. By using the alreadydescribed one obtained by supporting ruthenium chloride on a carrier atthe outer surface, the process is conducted in the same manner as thatin the process for preparing a catalyst conducted in the catalysts (1),(2) and (3) of the present invention.

The catalyst comprising ruthenium oxide supported on a carrier at theouter surface can be prepared in the above manner.

The alkali used in the step of preliminarily impregnating the carrierwith an aqueous solution of an alkali preferably includes potassiumhydroxide, sodium hydroxide, ammonium carbonate and ammoniumhydrogencarbonate. The concentration of the alkali impregnated in thecarrier is usually from 0.01 to 4.0 N, and preferably from 0.1 to 3.0 N.When the time from impregnation of ruthenium chloride on the carrier,which is impregnated preliminarily with the alkali, to drying is long,the inside of the carrier is also impregnated with ruthenium chlorideand, therefore, a suitable time must be selected according to the kindand concentration of the alkali to be used. Usually, the catalyst isdried immediately after impregnation, or dried until 120 minutes afterimpregnation. Preferably, the catalyst is dried immediately afterimpregnation, or dried until 30 minutes after impregnation.

The catalyst of the present invention is an outer surface-supportedcatalyst obtained by supporting ruthenium oxide on a carrier at theouter surface, and the thickness of the layer for supporting rutheniumoxide is preferably less than 70% of a length from the surface of thecarrier as a base point to the center of the carrier particles, and morepreferably less than 60% of a length from the surface of the carrier asa base point to the center of the carrier particle. The process ofmeasuring the thickness of the layer for supporting ruthenium oxideincludes a process of cutting along the plane passing through the centerof the particles of the supported ruthenium oxide catalyst and measuringby using a magnifying glass having graduation , and a process of cuttingin the same manner and measuring by using X-ray microanalyser (EPMA).Since the ruthenium component is fixed to the carrier by impregnatingthe carrier with ruthenium chloride and drying, the ruthenium componentdoes not transfer largely in the step of preparing the catalyst.Therefore, the thickness of the ruthenium oxide layer is determined bymeasuring the thickness of the layer supporting ruthenium chloride atthe stage where the catalyst is impregnated and dried.

As described above, it is also preferable that a process uses a catalystobtained by supporting ruthenium oxide on a carrier containingmacropores at the outer surface, wherein said process combines to use aprocess for producing chlorine using a supported ruthenium oxidecatalyst containing macropores having a pore diameter of 0.03 to 8micrometer as the catalyst (7) with a process for producing chlorineusing an outer surface-supported catalyst obtained by supportingruthenium oxide on a carrier as the catalyst (8) at the outer surface.

The supported ruthenium catalyst using chromium oxide in the carrierused in the catalyst (9) of the present invention is a catalyst obtainedby supporting ruthenium on a chromium oxide carrier.

Ruthenium to be supported include ruthenium oxide, ruthenium chlorideand metal ruthenium. A catalyst obtained by calcining the solid, whichis obtained by supporting ruthenium chloride or metal ruthenium on acarrier, can also be used. Preferable catalyst includes ruthenium oxidecatalyst supported on chromium oxide, ruthenium chloride catalystsupported on chromium oxide, a catalyst obtained by calcining rutheniumchloride catalyst supported on chromium oxide, metal ruthenium catalystsupported on chromium oxide, and catalyst obtained by calcining metalruthenium oxide catalyst supported on chromium oxide. More preferablecatalyst includes ruthenium oxide catalyst supported on chromium oxide,and a catalyst obtained by calcining ruthenium chloride catalystsupported on chromium oxide. More preferable catalyst includes rutheniumoxide catalyst supported on chromium oxide obtained by calciningruthenium hydroxide catalyst supported on chromium oxide, and a catalystobtained by calcining ruthenium chloride catalyst supported on chromiumoxide.

The process of supporting ruthenium includes impregnation process, ionexchange process and precipitation supporting process. Among them,impregnation process and precipitation supporting process are preferred.A weight ratio of ruthenium to the carrier is preferably within a rangefrom 0.1/99.9 to 20/80, and preferably from 0.5/99.5 to 10/90. When theamount of ruthenium is too small, the activity is lowered sometimes. Onthe other hand, when the amount of ruthenium is too large, the price ofthe catalyst becomes high sometimes.

The process of calcining the catalyst obtained by supporting rutheniumon the carrier includes process of heating to 200-500° C. in a gascontaining oxygen. The gas containing oxygen includes air and airdiluted with nitrogen. Preferable calcination temperature is from 280 to500C, and more preferably from 300 to 450° C. The calcination time isusually from 30 minutes to 10 hours.

The third component other than the ruthenium compound may also be added,and the third component includes, for example, palladium compound,copper compound, chromium compound, vanadium compound, nickel compound,alkali metal compound, rare earth compound, manganese compound andalkali earth compound. The amount of the third component to be added ispreferably form 0.1 to 10% by weight in terms of a proportion to thecarrier.

The chromium oxide carrier means chromium oxide alone, or a mixture ofchromium oxide and an oxide of element, or chromium mixed oxide. Theoxide of the element to be mixed with chromium oxide includes alumina,silica, silica-alumina, zeolite, diatomaceous earth, titanium oxide andzirconium oxide. The chromium mixed oxide includes chromia-silica,chromia-alumina, chromia-titania and chromia-zirconia. A weight ratio ofthe additives to chromium oxide is usually within a range from 0/100 to50/50, and preferably from 0/100 to 30/70. The proportion of chromiumcontained in the chromium mixed oxide is usually not less than 10% byweight, and preferably not less than 50% by weight.

Preferable chromium oxide carrier includes chromium oxide andchromia-titania. More preferable chromium oxide carrier is chromiumoxide alone.

The chromium oxide carrier can be used in the form of a powder, or canalso used after molding. The chromium carrier may be a commerciallyavailable one, and may also be prepared by using a chromium compound.

The process for preparing the catalyst includes various processes. Forexample, the process for preparing the catalyst obtained by calciningthe ruthenium chloride supported on chromium oxide includes thefollowing preparation process. That is, there can be used a process ofdissolving ruthenium chloride such as commercially available rutheniumchloride hydrate (RuCl₃.nH₂O) in a solvent, impregnating a chromiumoxide carrier with the resulting solution, and drying and calcining.

The solvent in which ruthenium chloride is dissolved includes water,hydrochloric acid, and an organic solvent such as methanol, and water orhydrochloric acid is preferred. The amount of ruthenium chloride to beimpregnated is usually from 0.1 to 20% by weight, and preferably from0.5 to 10% by weight, in terms of ruthenium. The drying temperature isusually from 50 to 100° C. The calcination temperature is usually from200 to 600° C., preferably from 280 to 500° C., and more preferably from300 to 450° C. The calcination atmosphere includes gas containing oxygenand nitrogen, preferably gas containing oxygen. Preferable examples ofthe gas containing oxygen include air. The calcination time is usuallyfrom 30 minutes to 10 hours.

The process for preparing the ruthenium oxide catalyst supported onchromium oxide includes the following preparation process, that is, aprocess of suspending a chromium oxide carrier in a solution obtained bydissolving ruthenium chloride such as commercially available rutheniumchloride hydrate (RuCl₃.nH₂O) in a solvent, adding an alkali,hydrolyzing ruthenium chloride to form ruthenium hydroxide resulting insupporting it on the carrier by precipitation, and oxidizing thesupported one to obtain a ruthenium oxide catalyst supported on chromiumoxide. The solvent in which ruthenium chloride is dissolved includeswater, aqueous hydrochloric acid solution, and an organic solvent suchas methanol, and water or an aqueous hydrochloric acid solution ispreferred.

The alkali includes aqueous solution of hydroxide of alkali metal,ammonia, carbonate of alkali metal, and carbonate of ammonia, and anaqueous solution of hydroxide of an alkali metal is preferred.

Preferable process of oxidizing supported ruthenium hydroxide includes aprocess of calcining in an air.

The calcination temperature is preferably from 280 to 500° C., and morepreferably from 300 to 450° C. The calcination can also be conducted intwo stages. When the calcination is conducted in two stages, the firststage is preferably conducted at low temperature ranging from 150 to300° C. The calcination time is usually from 30 minutes to 10 hours.

The amount of ruthenium oxide to be supported is usually from 0.1 to 20%by weight, and preferably from 0.5 to 10% by weight, in terms ofruthenium.

The process for preparing a ruthenium oxide catalyst supported onchromium oxide also includes the following preparation process.

That is, preferable examples thereof include a process of impregnating achromium oxide carrier with an aqueous ruthenium chloride solution,adding an alkali, hydrolyzing ruthenium chloride to deposit rutheniumhydroxide on the carrier, and calcining it under air. The alkaliincludes aqueous solution of hydroxide of alkali metal, ammonia,carbonate of alkali metal, and carbonate of ammonia, and an aqueoussolution of hydroxide of an alkali metal is preferred. Preferableexamples of the calcination conditions include the above conditions.

As described above, preferable examples of the ruthenium oxide catalystsupported on chromium oxide include catalyst obtained by supportingruthenium hydroxide on a carrier and calcining the supported one underair.

It can be confirmed by X-ray analysis and analysis by XPS (X-rayphotoelectron spectroscopy) that the ruthenium compound was convertedinto ruthenium oxide.

The process for preparing metal ruthenium catalyst supported on chromiumoxide includes a process of impregnating a chromium oxide carrier withan aqueous ruthenium chloride solution, and reducing by using a reducingagent such as hydrogen, and preferable examples thereof include aprocess of impregnating a chromium oxide carrier with a solutionobtained by dissolving commercially available ruthenium chloride hydrate(RuCl₃.nH₂O) in a solvent, drying the impregnated one, and reducing bycalcining in a gas containing hydrogen or reducing by using a reducingagent such as sodium boron hydride or hydrazine.

The process for preparing a catalyst obtained by calcining a metalruthenium catalyst supported on chromium oxide includes the followingpreparation process. That is, preferable examples thereof include aprocess of calcining the above-mentioned metal ruthenium catalystsupported on chromium oxide in a gas containing oxygen. The calcinationtemperature is preferably from 280 to 500° C., and more preferably from300 to 450° C. The calcination time is usually from 30 minutes to 10hours.

It is an object of the present invention to obtain chlorine by oxidizinghydrogen chloride with oxygen using the above catalyst. The reactionsystem used to obtain chlorine includes, for example, a flow system suchas fixed bed or fluidized bed, and a gas phase reaction such as fixedbed flow system and gas phase fluidized bed flow system can bepreferably used. The fixed bed system has an advantage that separationbetween the reaction gas and catalyst is not required and that highconversion can be accomplished because a raw gas can be sufficientlycontacted with a catalyst. The fluidized bed system has an advantagethat heat in the reactor can be sufficiently removed and temperaturedistribution width in the reactor can be minimized

When the reaction temperature is high, volatilization of ruthenium oxidein a highly oxidized state occurs. Therefore, the reaction is preferablyconducted at low temperature and the reaction temperature is usuallyfrom 100 to 500° C., preferably from 200 to 400° C., more preferablyfrom 200 to 380° C. The reaction pressure is usually from aboutatmospheric pressure to 50 atm. As the raw material of oxygen, an airmay be used as it is, or pure oxygen may also be used. Since othercomponents are also discharged simultaneously when an inert nitrogen gasis discharged out of the plant , pure oxygen containing no inert gas ispreferable. The theoretic molar amount of oxygen based on hydrogenchloride is ¼ mol, but oxygen is usually fed in an amount that is 0.1-10times of the theoretical amount. In the case of the fixed bed gas phaseflow system, the amount of the catalyst to be used is usually from about10 to 20000 h⁻¹ in terms of a ratio (GHSV) to a feed rate of hydrogenchloride as the raw material under atmospheric pressure. GHSV means gashourly space velocity which is a ratio of a volume of feed hydrogenchloride gas (1/h) to volume of catalyst (1).

The present invention which relates to a process for producing asupported ruthenium oxide catalyst will be described below.

The supported ruthenium oxide catalyst produced in the catalyst (1) ofthe present invention is a supported ruthenium oxide catalyst preparedin a ruthenium compound supporting step, an alkali treating step, areducing compound treating step and an oxidizing step, more preferably asupported ruthenium oxide catalyst prepared in a ruthenium halidesupporting step, an alkali treating step, a reducing compound treatingstep and an oxidizing step, and still more preferably a supportedruthenium oxide catalyst prepared in a ruthenium halide supporting step,an alkali treating step, a reducing compound treatment step, an alkalimetal chloride adding step and an oxidizing step.

The supported ruthenium oxide catalyst produced in the catalyst (2) ofthe present invention is a supported ruthenium oxide catalyst obtainedby the steps which comprises supporting a ruthenium compound on acarrier, treating the supported one by using a reducing agent to formruthenium having an oxidation number of 1 to less than 4 valence, andoxidizing the resulted one.

The process for preparing the supported ruthenium oxide catalystincludes various processes. For example, a process for preparing acatalyst comprising ruthenium oxide having an oxidation number of 4valence supported on a carrier can be prepared by supporting rutheniumchloride on a carrier, hydrolyzing the supported one by using an alkali,and calcining under air. Alternatively, a process for preparing acatalyst comprising supported ruthenium oxide having an oxidation numberof 4 valence can also be prepared by supporting ruthenium chloride on acarrier, reducing the supported one by using various reducing agents toform ruthenium having a valence of 0, and calcining under air. It isalso possible to exemplify a preparation example of a supportedruthenium oxide catalyst comprising supported ruthenium oxide having anoxidation number of 4, which is prepared by supporting rutheniumchloride on a carrier, treating the supported one by using a mixedsolution of various reducing compounds and basic compounds, or treatingby using an aqueous alkali solution of a reducing compound, or treatingby using various reducing agents, thereby to form a ruthenium compoundhaving an oxidation number of 1 to less than 4 valence, and calciningunder air. The catalyst prepared by this preparation process can beexemplified as a preparation example which is most active to theoxidizing reaction of hydrogen chloride. The process of adjusting theoxidation number of the ruthenium compound supported on the carrierwithin a range from 1 to less than 4 valence includes various processes,for example, process of treating by using a mixed solution of a reducingcompound and a basic compound, process of treating by using an alkalisolution of a reducing compound, process of treating by using anorganolithium compound, an organosodium compound or an organopotassiumcompound, process of treating by using an organoaluminum compound,process of treating by using an organomagnesium compound, and process oftreating by using hydrogen. When using these reducing agents in anexcess amount, the ruthenium compound is reduced to the valence of 0and, therefore, it is necessary to use it in a suitable amount.

The process of measuring the oxidation number of the supported rutheniumincludes various processes. For example, since nitrogen is mainlygenerated when using hydrazine as the reducing agent, the valence numberof ruthenium can be determined by the amount of nitrogen generated.

The reaction scheme will be shown below.

For example, when the ruthenium compound is reduced by using hydrazineunder the conditions of an aqueous alkali solution, a hydroxide ofruthenium is formed. Therefore, the oxidation number of ruthenium canalso be determined by measuring a ratio of ruthenium to oxygen andchlorine bound to ruthenium due to elemental analysis after dehydrationunder vacuum.

In the present invention, the oxidation number of ruthenium wasdetermined from the amount of nitrogen generated by using the scheme(1).

The common part with the processes (1) and (2) for producing thecatalyst will be explained.

The carrier includes, for example, oxides and mixed oxides of elements,such as titanium oxide, alumina, zirconium oxide, silica, titanium mixedoxide, zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxideand the like. Preferable carriers are titanium oxide, alumina, zirconiumoxide and silica, and more preferable carrier is titanium oxide.

The ruthenium compound to be supported on the carrier include compounds,for example, ruthenium chloride such as RuCl₃ and RuCl₃ hydrate;chlororuthenate such as K₃RuCl₆, [RuCl₆]³⁻ and K₂RuCl₆; chlororuthenatehydrate such as [RuCl₅(H₂O)₄]²⁻ and [RuCl₂(H₂O)₄]⁺; salt of ruthenicacid, such as K₂RuO₄; rutheniumoxy chloride such as Ru₂OCl₄, Ru₂OCl₅ andRu₂OCl₆; salt of rutheniumoxy chloride, such as K₂Ru₂OCl₁₀ andCs₂Ru₂OCl₄; ruthenium-ammine complex such as [(Ru(NH₃)₆]²⁺, [Ru(NH₃)₆]³⁺and [Ru(NH₃)₅H₂O]²⁺; chloride and bromide of ruthenium-ammine complex,such as [Ru(NH₃)₅Cl]²⁺, [Ru(NH₃)₆] Cl₂, [Ru(NH₃)₆]Cl₃ and [Ru(NH₃)₆]Br₃;ruthenium bromide such as RuBr₃ and RuBr₃ hydrate; otherruthenium-organoamine complex; ruthenium-acetylacetonato complex;ruthenium-carbonyl complex such as Ru(CO)₅ and Ru₃(CO)₁₂; rutheniumorganic acid salt such as [Ru₃O(OCOCH₃)₆(H₂O)₃]OCOCH₃ hydrate andRu₂(RCOO)₄Cl(R: alkyl group having carbon atoms of 1-3);ruthenium-nitrosyl complex such as K₂[RuCl₅(NO)]], [Ru(NH₃)₅(NO)]Cl₃,[(Ru(OH) (NH₃)₄(NO)](NO₃)₂ and Ru(NO) (NO₃)₃; and ruthenium-phosphinecomplex. Preferable ruthenium compounds are ruthenium halide compounds,for example, ruthenium chloride such as RuCl₃ and RuCl₃ hydrate andruthenium bromide such as RuBr₃ and RuBr₃ hydrate. Preferable rutheniumhalide includes ruthenium chloride such as RuCl₃ and RuCl₃ hydrate andruthenium bromide such as RuBr₃ and RuBr₃ hydrate. More preferred one isa ruthenium chloride hydrate.

The process of supporting the ruthenium compound on the carrierincludes, for example, impregnation process and equilibrium adsorptionprocess.

The alkali used in the alkali treating step includes, for example,hydroxide, carbonate and hydrogencarbonate of alkali metal; aqueoussolution or solution of an organic solvent such as alcohol of ammonia,ammonium carbonate and ammonium hydrogencarbonate. As the alkali, forexample, hydroxide, carbonate and hydrogencarbonate of alkali metal arepreferably used. As the solvent, water is preferably used. It is also apreferable process to use one obtained by dissolving a reducing compoundin an alkali solution.

The reducing compound used in the reducing compound treating stepincludes, for example, hydrazine, methanol, ethanol, formaldehyde,hydroxylamine or formic acid, or an aqueous solution of hydrazine,methanol, ethanol, formaldehyde, hydroxylamine or formic acid, or asolution of an organic solvent such as alcohol. Preferred are hydrazine,methanol, ethanol, formaldehyde, and solutions of hydrazine, methanol,ethanol and formaldehyde. More preferred are hydrazine and a solution ofhydrazine. The reducing compound used for treating the rutheniumcompound supported on the carrier includes, for example, a compoundhaving a redox potential of −0.8 to 0.5 V, a solution thereof, and asolution of an organic solvent such as alcohol. Now a standard electrodepotential is used in place of the redox potential. Among the compoundslisted above, a standard electrode potential of hydrazine is −0.23 V,that of formaldehyde is 0.056 V and that of formic acid is −0.199 V,respectively. It is also a preferable process to use an aqueous alkalisolution of the reducing compound.

The basic compound for preparing the catalyst (2) includes, for example,ammonia; amine such as alkyl amine, pyridine, aniline, trimethylamineand hydroxyl amine; alkali metal hydroxide such as potassium hydroxide,sodium hydroxide and lithium hydroxide; alkali metal carbonate such aspotassium carbonate, sodium carbonate and lithium carbonate; hydroxideof quaternary ammonium salt; and alkyl aluminum such as triethylaluminum.

The process of treating by using a reducing compound includes, forexample, a process of dipping one obtained in the alkali treating stepin a reducing compound or a solution of a reducing compound, orimpregnating with a reducing compound or a solution of a reducingcompound. It is also a preferable process to use an aqueous alkalisolution of the reducing compound.

A process of treating by using a reducing compound or an aqueous alkalisolution of a reducing compound, and adding an alkali metal chloride isalso a preferable process.

The process of oxidizing includes, for example, process of calciningunder air.

A weight ratio of ruthenium oxide to the carrier is preferably within arange from 0.1/99.9 to 20.0/80.0, more preferably from 0.5/99.5 to15.0/85.0, and still more preferably from 1.0/99.0 to 15.0/85.0. Whenthe ratio of ruthenium oxide is too low, the activity is loweredsometimes. On the other hand, when the ratio of ruthenium oxide is toohigh, the price of the catalyst becomes high sometimes. Examples of theruthenium oxide to be supported include ruthenium dioxide, rutheniumhydroxide and the like.

The embodiment of the process for preparing the supported rutheniumoxide catalyst produced by the processes (1) and (2) for producing thecatalyst of the present invention include a preparation processcomprising the following steps:

a ruthenium compound supporting step: step of supporting a rutheniumcompound on a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium compound supporting step;

a reducing compound treating step: step of treating one obtained in thealkali treating step by using a reducing compound; and

an oxidizing step: step of oxidizing one obtained in the reducingcompound treating step.

It is also preferred to use an aqueous alkali solution of a reducingcompound to simultaneously conduct the alkali treating step and thereducing compound treating step in the above step.

Preferred embodiment of the process of preparing the supported rutheniumoxide catalyst produced by the processes (1) and (2) for producing thecatalyst of the present invention include a preparation processcomprising the following steps:

a ruthenium halide compound supporting step: step of supporting aruthenium halide compound on a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide compound supporting step;

a reducing compound treating step: step of treating one obtained in thealkali treating step by using hydrazine, methanol, ethanol orformaldehyde; and

an oxidizing step: step of oxidizing one obtained in the reducingcompound treating step.

It is also preferred to use an aqueous alkali solution of a reducingcompound to simultaneously conduct the alkali treating step and thereducing compound treating step in the above step.

More preferred embodiment of the process of preparing the supportedruthenium oxide catalyst produced by the processes (1) and (2) forproducing the catalyst of the present invention include a preparationprocess comprising the following steps:

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide supporting step;

a hydrazine treating step: step of treating one obtained in the alkalitreating step by using hydrazine; and

an oxidizing step: step of oxidizing one obtained in the hydrazinetreating step.

It is also preferred to use an aqueous alkali solution of hydrazine tosimultaneously conduct the alkali treating step and the hydrazinetreating step in the above step.

Still more preferred embodiment of the process of preparing thesupported ruthenium oxide catalyst produced by the processes (1) and (2)for producing the catalyst of the present invention include apreparation process comprising the following steps:

a ruthenium halide supporting step: step of supporting ruthenium halideon a carrier of a catalyst;

an alkali treating step: step of adding an alkali to one obtained in theruthenium halide supporting step;

a hydrazine treating step: step of treating one obtained in the alkalitreating step by using hydrazine;

an alkali metal chloride-adding step: step of adding an alkali metalchloride to one obtained in the hydrazine treating step; and

an oxidizing step: step of oxidizing one obtained in the alkali metalchloride adding step.

It is also preferred to use an aqueous alkali solution of hydrazine tosimultaneously conduct the alkali treating step and the hydrazinetreating step in the above step.

The ruthenium halide supporting step is a step of supporting rutheniumhalide on a carrier of a catalyst. The ruthenium compound to besupported on the carrier includes, for example, already listed variousruthenium compounds. Among them, preferred examples thereof are halidesof ruthenium, for example, ruthenium chloride such as RuCl₃ and RuCl₃hydrate and ruthenium bromide such as RuBr₃ and RuBr₃ hydrate. Preferredexamples of the ruthenium halide include ruthenium chloride such asRuCl₃ and RuCl₃ hydrate and ruthenium bromide such as RuBr₃ and RuBr₃hydrate. More preferred one is a ruthenium chloride hydrate.

The amount of ruthenium halide used in the ruthenium halide supportingstep is usually an amount corresponding to a preferable weight ratio ofruthenium oxide to the carrier. That is, is supported by using a processof impregnating a solution of ruthenium halide with already listedcarrier or adsorbing said solution to already listed carrier. As thesolvent, for example, water and an organic solvent such as alcohol areused, and water is preferred. The impregnated one can be dried, and canalso be treated by using an alkali without being dried, but it ispreferable the impregnating one is dried. Regarding the conditions fordrying the impregnated one, the drying temperature is preferably from 50to 200° C. and the drying time is preferably from 1 to 10 hours.

The alkali treating step is a step for adding an alkali to one obtainedin the ruthenium halide supporting step. The alkali used in the alkalitreating step includes, for example, hydroxide, carbonate andhydrogencarbonate of alkali metal; aqueous solution of ammonia, ammoniumcarbonate and ammonium hydrogencarbonate; and solution of an organicsolvent such as alcohol. As the alkali, for example, hydroxide,carbonate and hydrogencarbonate of alkali metal are preferably used. Asthe solvent, for example, water is preferably used. The concentration ofthe alkali varies depending on the kind of alkali to be used, but ispreferably from 0.1 to 10 mol/l.

Regarding a molar ratio of the ruthenium halide to the alkali is, forexample, 3 mol of sodium hydrooxide is equivalent to 1 mol of rutheniumhalide in case of using sodium hydroxide. Preferably, the alkali is usedin the amount of 0.1-20 times equivalent per that of ruthenium halide.The process of adding the alkali include a process of impregnating witha solution of the alkali or a process of dipping in a solution of thealkali. The time of impregnation with the solution of the alkali isusually within 60 minutes. Since the activity of the catalyst decreaseswhen the impregnation time is long, the impregnation time is preferablywithin 10 minutes. The impregnation temperature is preferably from 0 to100° C., and more preferably from 10 to 60° C.

The hydrazine treating step is a step of treating one obtained in thealkali treating step by using hydrazine. The process of treating byusing hydrazine includes, for example, a process of impregnating with asolution of hydrazine and a process of dipping in a solution ofhydrazine. The supported ruthenium halide treated by using the alkali inthe previous step and an alkali solution may be added to a hydazinesolution in a state of being mixed, or may be added to the hydazinesolution after the alkaline solution was separated by filtration. Apreferable process is a process of impregnating the supported rutheniumhalide with the alkali and immediately adding to the hydrazine solution.The concentration of hydrazine used in the hydrazine treating step ispreferably not less than 0.1 mol/l.Hydrazine hydrate such as hydrazinemonohydrate may be used as it is. Alternatively, it is used as asolution of an organic solvent such as alcohol. Preferably, an aqueoussolution of hydrazine or hydrazine hydrate is used. Anhydride and amonohydrate of hydrazine can also be used. Regarding a molar ratio ofruthenium halide to hydrazine, hydrazine is used in the amount of 0.1 to20 mol per mol of ruthenium halide. The time of impregnation with thesolution of hydrazine is preferably from 5 minutes to 5 hours, and morepreferably from 10 minutes to 2 hours. The temperature is preferablyfrom 0 to 100° C., and more preferably from 10 to 60° C. After dippingin the hydrazine solution, the dipping one is preferably separated fromthe solution by filtration.

It is also preferred to use an aqueous alkali solution of hydrazine tosimultaneously conduct the alkali treating step and hydrazine treatingstep in the above step. Preferable process includes a process of slowlydipping one obtained in the ruthenium halide supporting step to thoseprepared by mixing a preferable amount of the alkali with a preferableamount of hydazine, and treating for 5 minutes to 5 hours.

More preferable process includes a process of washing a solid producedin the alkali treating step and hydrazine treating step, thereby toremove the alkali and hydrazine, and then drying, adding an alkali metalchloride in the following alkali metal chloride adding step, drying, andoxidizing.

More preferable process includes a process of washing a solid producedin the alkali treating step and hydrazine treating step by using anaqueous solution of an alkali metal chloride, and then drying, andoxidizing. This process is preferred because the removal of the alkaliand hydrazine, and the addition of the alkali metal chloride can beconducted in the same step.

The alkali metal chloride adding step is a step of adding an alkalimetal chloride to one obtained in the alkali treating step and hydrazinetreating step. This step is not an indispensable step to prepare thesupported ruthenium oxide catalyst, but the activity of the catalyst isfurther improved by conducting said step. That is, the resulting solidis oxidized by the following oxidizing step, but it is a preferablepreparation example to convert it into highly active supported rutheniumoxide by oxidizing the resulting solid treated with the alkali andhydrazine in the presence of an alkali metal salt.

The alkali metal chloride includes, for example, chloride of alkalimetal, such as potassium chloride and sodium chloride. Preferablealkaline metal chlorides are potassium chloride and sodium chloride, andmore preferable one is potassium chloride. A molar ratio of the alkalimetal salt to ruthenium is preferably from 0.01 to 10, and morepreferably from 0.1 to 5.0. When the amount of the alkali metal saltused is too small, sufficient highly active catalyst is not obtained. Onthe other hand, when the amount of the alkali metal salt used is toolarge, the cost becomes high from an industrial point of view.

The process of impregnating with the aqueous alkali metal chloridesolution includes a process of impregnating the resulting supportedruthenium one obtained by washing, drying, treating by using hydrazine,but more preferable process includes a process of impregnating theresulting supported ruthenium one treated with the alkali and hydrazineby washing with an aqueous alkali metal chloride solution without beingwashed with water.

For the purpose of adjusting the pH in the case of washing the resultingsupported ruthenium one, hydrochloric acid can also be added to anaqueous solution of the alkali metal chloride. The concentration of theaqueous solution of the alkali metal chloride is preferably from 0.01 to10 mol/l, and more preferably from 0.1 to 5 mol/l.

The purpose of washing lies in removal of the alkali and hydrazine, butthe alkali and hydrazine can also be remained as far as the effect ofthe present invention is not adversely affected.

After impregnating with the alkali metal chloride, the catalyst isusually dried. Regarding the drying conditions, the drying temperatureis preferably from 50 to 200° C. and the drying time is preferably from1 to 10 hours.

The oxidizing step is a step of oxidizing one obtained in the alkalitreating step and hydrazine treating step (in the case of using noalkali metal chloride adding step), or a step of oxidizing one obtainedin the alkali metal chloride adding step (in the case of using thealkali metal chloride adding step). The oxidizing step can include aprocess of calcining under air. It is a preferable preparation exampleto convert it into highly active supported ruthenium oxide by calciningone treated with the alkali and hydrazine in the presence of an alkalimetal salt in a gas containing oxygen. A gas containing oxygen usuallyincludes air.

The calcination temperature is preferably from 100 to 600° C., and morepreferably from 280 to 450° C. When the calcination temperature is toolow, particles formed by the alkali treatment and hydrazine treatmentare remained in a large amount in the form of a ruthenium oxideprecursor and, therefore, the activity of the catalyst becomesinsufficient sometimes. On the other hand, when the calcinationtemperature is too high, agglomeration of ruthenium oxide particlesoccur and, therefore, the activity of the catalyst is lowered. Thecalcination time is preferably from 30 minutes to 10 hours.

In this case, it is important to calcine in the presence of the alkalimetal salt. By using this process, it is possible to obtain higheractivity of the catalyst because that process of forming more fineparticle of ruthenium oxide, comparing the process which includescalciing in the substantially absence of the alkali metal salt.

By the calcination, the particles supported on the carrier, which areformed by the alkali treatment and hydrazine treatment, are convertedinto a supported ruthenium oxide catalyst. It can be confirmed byanalysis such as X-ray diffraction and XPS (X-ray photoelectronspectroscopy) that the particles formed by the alkali treatment andhydrazine treatment were converted into ruthenium oxide. Incidentally,substantially total amount of particles formed by the alkali treatmentand hydrazine treatment are preferably converted into ruthenium oxide,but the particles formed by the alkali treatment and hydrazine treatmentcan be remained as far as the effect of the present invention is notadversely affected.

The process of oxidizing one treated with the alkali and hydrazine,washing the remained alkali metal chloride, and drying the washed one isa preferable preparation process. It is preferred that the alkali metalchloride contained on calcination is sufficiently washed with water. Theprocess of measuring the alkali metal chloride after washing includes aprocess of examining the presence/absence of white turbidity by addingan aqueous silver nitrate solution to the filtrate. However, the alkalimetal chloride may be remained as far as the effect of the presentinvention is not adversely affected.

According to a preferable preparation process, the washed catalyst isthen dried. Regarding the drying conditions, the drying temperature ispreferably from 50 to 200° C. and the drying time is preferably from 1to 10 hours.

The supported ruthenium oxide catalyst produced by the above steps ishighly active, and the activity was higher than that of the catalystprepared by oxidizing a catalyst obtained by reducing ruthenium chloridewith hydrogen. Furthermore, a catalyst obtained by previously treatingruthenium chloride by using an alkali, treating by using hydrazine, ortreating by using alkali and hydrazine simultaneously, and oxidizingshowed higher activity than that of a catalyst obtained by treatingruthenium chloride with hydrazine, and oxidizing.

The supported ruthenium oxide catalyst produced by the process (3) forproducing the catalyst of the present invention is a supported rutheniumoxide catalyst using titanium oxide containing rutile titanium oxide asa carrier. As the titanium oxide, for example, rutile titanium oxide,anatase titanium oxide and non-crystal titanium oxide are known. Thetitanium oxide containing rutile titanium oxide used in the presentinvention refers to one containing a rutile crystal by measuring a ratioof the rutile crystal to the anatase crystal in the titanium oxide byX-ray diffraction analysis. The measuring process will be described indetail hereinafter. When the chemical composition of the carrier used inthe present invention is composed of titanium oxide alone, theproportion of the rutile crystal is determined from a ratio of therutile crystal to the anatase crystal in the titanium oxide by usingX-ray diffraction analysis. In the present invention, a mixed oxide ofthe titanium oxide and other metal oxide is also used. In that case, theproportion of the rutile crystal is determined by the following process.The oxide to be mixed with the titanium oxide includes oxides ofelements, and preferred examples thereof include alumina, zirconiumoxide and silica. The proportion of the rutile crystal in the mixedoxide is also determined from the ratio of the rutile crystal to theanatase crystal in the titanium oxide by using X-ray diffractionanalysis, but it is necessary to contain the rutile crystal. In thiscase, the content of the oxide other than the titanium oxide in themixed oxide is within a range from 0 to 60% by weight. Preferred carrierincludes titanium oxide which does not contain a metal oxide other thantitanium oxide.

It is necessary that the titanium oxide contains the rutile crystal. Thecontent of the rutile crystal is preferably not less than 10%, morepreferably not less than 30%, and most preferably not less than 80%.

The process for preparing the titanium oxide containing the rutilecrystal includes various processes. In general, the following processesare exemplified. For example, when using titanium tetrachloride as a rawmaterial, titanium tetrachloride is dissolved by adding dropwise inice-cooled water, and then neutralized with an aqueous ammonia solutionto form titanium hydroxide (ortho-titanic acid). Thereafter, the formedprecipitate was washed with water to remove a chlorine ion. In thatcase, when the temperature on neutralization becomes higher than 20° C.or the chlorine ion is remained in the titanium oxide after washing,conversion into a stable rutile crystal is liable to occur oncalcination. When the calcination temperature becomes not less than 600°C., conversion into rutile occurs (Catalyst Preparation Chemistry, 1989,page 211, Kodansha). For example, a reaction gas is prepared by passingan oxygen-nitrogen mixed gas through a titanium tetrachloride evaporatorand the reaction gas is introduced into a reactor. The reaction betweentitanium tetrachloride and oxygen starts at a temperature of about 400°C. and titanium dioxide formed by the reaction of a TiCl₄-O₂ system ismainly an anatase type. However, when the reaction temperature becomesnot less than 900° C., formation of a rutile type can be observed(Catalyst Preparation Chemistry, 1989, page 89, Kodansha). Thepreparation process includes, for example, a process of hydrolyzingtitanium tetrachloride in the presence of ammonium sulfate and calcining(e.g. Shokubai Kougaku Kouza 10, Catalyst Handbook by Element, 1978,page 254, Chijin Shokan) and a process of calcining an anatase titaniumoxide (e.g. Metal Oxide and Mixed Oxide, 1980, page 107, Kodansha).Furthermore, rutile titanium oxide can be obtained by a process forhydrolyzing an aqueous solution of titanium tetrachloride by heating.Rutile titanium oxide is also formed by previously mixing an aqueoustitanium compound solution of titanium sulfate or titanium chloride witha rutile titanium oxide powder, hydrolyzing the mixture by heating orusing an alkali, and calcining at low temperature of about 500° C.

The process of determining the proportion of the rutile crystal in thetitanium oxide includes a X-ray diffraction analysis and, as a X-raysource, various X-ray sources can be used. For example, a K α ray ofcopper is used. When using the K α ray of copper, the proportion of therutile crystal and the proportion of the anatase are respectivelydetermined by using an intensity of a diffraction peak of 2θ=27.5 degreeof the plane (110) and an intensity of a diffraction peak of 2θ=25.3degree of the plane (101). The carrier used in the present invention isone having a peak intensity of the rutile crystal and a peak intensityof the anatase crystal, or one having a peak intensity of the rutilecrystal. That is, the carrier has both of a diffraction peak intensityof the rutile crystal and a diffraction peak of the anatase crystal, orhas only a diffraction peak of the rutile crystal. Preferred carrier isone wherein a proportion of the peak intensity of the rutile crystal tothe total of the peak intensity of the rutile crystal and the peakintensity of the anatase crystal is not less than 10%. Also in thesupported ruthenium oxide catalyst using the titanium oxide carriercontaining rutile titanium oxide, an amount of an OH group contained inthe carrier is preferably similar amount to the catalyst which isproduced by the process (4) of the present invention. Although thedetails will be described with regard as the process (4) for producingthe catalyst of the present invention, the amount of the OH group of thetitanium oxide of the carrier used in the catalyst is usually from0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier), preferably from 0.2×10⁻⁴ to 20×10⁻⁴(mol/g-carrier), and more preferably from 3.0×10⁻⁴ to 15×10⁻⁴(mol/g-carrier).

The supported ruthenium oxide catalyst produced by the process (4) forproducing the catalyst of the present invention is a supported rutheniumoxide catalyst obtained by the steps which comprises supporting aruthenium compound on a carrier, treating the supported one by using areducing compound or a reducing agent in a liquid phase, and oxidizingthe resulted one, wherein titanium oxide containing an OH group in anamount of 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier) per unit weight of acarrier is used as the carrier. The carrier includes, for example,rutile crystal carrier, anatase crystal carrier and non-crystal carrier.Preferable carriers are rutile crystal carrier and anatase crystalcarrier, and more preferable one is rutile crystal carrier. It isgenerally known that a hydroxyl group represented by OH bound to Tiexists on the surface of the titanium oxide. The titanium oxide used inthe present invention is one containing an OH group, and the process ofmeasuring the content of OH group will be described in detailhereinafter. When the chemical composition of the carrier used in thepresent invention is consisting essentially of titanium oxide alone, itis determined from the content of the OH group in the titanium oxide. Inthe present invention, a mixed oxide of the titanium oxide and othermetal oxide is also used. The oxide to be mixed with the titanium oxideincludes oxides of elements, and preferred examples thereof includealumina, zirconium oxide and silica. In that case, the content of theoxide other than the titanium oxide in the mixed oxide is within a rangefrom 0 to 60% by weight. Also this case, the content of the OH group perunit weight of the carrier contained in the carrier is determined by themeasuring process which is also described in detail hereinafter.Preferred carrier is titanium oxide which does not contain the metaloxide other than the titanium oxide.

When the content of the OH group of the carrier is large, the carrierand supported ruthenium oxide may react each other, resulting indeactivation. On the other hand, when the content of the OH group of thecarrier is small, the activity of the catalyst is lowered sometimes bysintering of the supported ruthenium oxide and the other phenomenon.

The process of determining the content of the OH group of the titaniumoxide includes various processes. For example, a process using athermogravimetric process (TG) is exemplified. When using thethermogravimetric process, the temperature is kept constant and, afterremoving excess water in a sample, the sample is heated and the contentof the OH group is measured from a weight loss. According to thisprocess, the amount of the sample is small and it is difficult tomeasure with good accuracy. When heat decomposable impurities exist inthe carrier, there is a drawback that the actual content of the OH groupis not determined. When using the measurement of ignition loss (Igloss)for measuring the content of the OH group from the weight loss of thesample in the same manner, the measurement with high accuracy can beconducted if the amount of the sample is increased. However, aninfluence of the heat decomposable impurities is exerted similar to thecase of the thermogravimetric process. Furthermore, there is also adrawback that the weight loss obtained by the thermogravimetric processand ignition loss measurement also includes the bulk OH group contentwhich is not effective on preparation of the catalyst.

A process using sodium naphthalene is also exemplified. According tothis process, an OH group in a sample is reacted with sodium naphthaleneas a reagent and then the content of the OH group is measured from thetitration amount of sodium naphthalene. In this case, since a change inconcentration of the reagent for titration and a trace amount of waterexert a large influence on the results, the measuring results areinfluenced by the storage state of the reagent. Therefore, it is verydifficult to obtain a value with good accuracy.

A titration process using an alkyl alkali metal is also exemplified. Thetitration process using the alkyl alkali metal includes a preferableprocess of suspending a titanium oxide carrier or a titanium oxidecarrier powder in a dehydrated solvent, adding dropwise an alkyl alkalimetal in a nitrogen atmosphere, and determining the amount of the OHgroup contained in the titanium oxide from the amount of hydrocarbongenerated. In that case, since an alkyl alkali metal and water containedin the dehydrated solvent react each other to generate hydrocarbon, thecontent of the OH group in the titanium oxide must be determined bysubtracting the generated amount from the measured value.

Most preferred process includes a process of suspending a titanium oxidecarrier or a titanium oxide carrier powder in a dehydrated toluene ,adding dropwise methyl lithium in a nitrogen atmosphere, and determiningthe amount of the OH group contained in the titanium oxide from theamount of methane generated, and the content of the OH group in thetitanium oxide catalyst of the present invention is a value obtained bythis process.

The measuring procedure includes, for example, the following process.First, a sample is previously dried under air atmosphere at atemperature of 150° C. for 2 hours and then cooled in a desiccator.Thereafter, a predetermined amount of the sample is transferred in aflask whose atmosphere was replaced by nitrogen, and then suspended inan organic solvent such as dehydrated toluene. The flask is ice-cooledto inhibit heat generation and, after adding dropwise methyl lithiumfrom a dropping funnel, the generated gas is collected and the volume atthe measuring temperature is measured. The content of the OH group thusdetermined, which is used in the catalyst, is usually from 0.1×10⁻⁴ to30×10⁻⁴ (mol/g-carrier), preferably from 0.2×10⁻⁴ to 20×10⁻⁴(mol/g-carrier), and more preferably from 3.0×10⁻⁴ to 15×10⁻⁴(mol/g-carrier).

The process of adjusting the amount of the OH group contained in thetitanium oxide carrier to a predetermined amount includes variousprocesses. For example, a calcination temperature and a calcination timeof the carrier are used for adjusting the OH group of the carrier. TheOH group in the titanium oxide carrier is eliminated by heating, and thecontent of the OH group can be controlled by changing the calcinationtemperature and calcination time. The calcination temperature of thecarrier is usually from 100 to 1000° C., and preferably from 150 to 800°C. The calcination time of the carrier is usually from 30 minutes to 12hours. In this case, it is necessary to pay attention to the point thatthe surface area of the carrier decreases with the increase of thecalcination temperature or the calcination time. When the titanium oxideis produced from a gas phase, one having small content of the OH groupcan be produced. Furthermore, when the titanium oxide is produced froman aqueous phase such as aqueous solution, one having large content ofthe OH group can be produced. Furthermore, a process of treating the OHgroup of the carrier by using an alkali and a process of reacting the OHgroup by using 1,1,1-3,3,3-hexamethyldisilazane are exemplified

The present invention relates to a process for producing a supportedruthenium oxide catalyst using the above carrier. A weight ratio ofruthenium oxide to the carrier is usually within a range from 0.1/99.9to 20.0/80.0, preferably from 0.5/99.5 to 15.0/85.0, and more preferablyfrom 1.0/99.0 to 15.0/85.0. When the ratio of ruthenium oxide is toolow, the activity is lowered sometimes. On the other hand, when theratio of ruthenium oxide is too high, the price of the catalyst becomeshigh sometimes. Examples of the ruthenium oxide to be supported includeruthenium dioxide, ruthenium hydroxide and the like.

The process for preparing the supported ruthenium oxide catalyst byusing the above carrier is a process comprising the steps of supportinga ruthenium compound on a carrier, treating the supported one by using areducing compound or a reducing agent in a liquid phase, and oxidizing.A process of treating the supported one reducing by using a reducingcompound or a reducing agent in a liquid phase includes, for example, aprocess of treating the supported one by using a reducing compound or areducing agent in a liquid phase which is conducted in the catalystsproduced (1), (2) of the present invention and in the catalysts reducedby a reducing agent such as sodium boron hydride, and the processdescribed below. That is, the process includes a process of suspendingone comprising the already described ruthenium compound supported on thecarrier in an aqueous phase or an organic solvent, and bubblinghydrogen, a process of treating by using an organolithium compound suchas butyl lithium, or an organosodium compound or an organopotassiumcompound in an organic solvent, a process of treating by using anorganoaluminum compound such as trialkyl aluminum, and a process oftreating by using an organomagnesium compound such as Grignard reagent.Furthermore, various organometallic compounds can be used and examplesthereof include alkali metal alkoxide such as sodium methoxide; alkalimetal naphthalene compound such as sodium naphthalene; azide compoundsuch as sodium azide; alkali amide compound such as sodium amide;organocalcium compound, organozinc compound; organoaluminum alkoxidesuch as alkyl aluminum alkoxide; organotin compound; organocoppercompound; organoboron compound; boranes such as borane and diborane;sodium ammonia solution; and carbon monoxide. Various organic compoundcan also be used and examples thereof include diazomethane, hydroquinoneand oxalic acid.

In a process for producing a supported ruthenium oxide catalyst, it ispreferable that the catalyst (1) or (2) is a supported ruthenium oxidecatalyst obtained by using titanium oxide containing not less than 10%by weight of rutile titanium oxide as a carrier. It is more preferablethat the catalyst (1) or (2) is a supported ruthenium oxide catalystobtained by using titanium oxide containing not less than 30% by weightof rutile titanium oxide as a carrier.

It is preferable that in the case of the catalyst (3) or (4), saidprocess comprises supporting a ruthenium compound on a carrier, reducingthe supported one by using a reducing hydrogenated compound, andoxidizing.

It is preferable that in the case of the catalyst (3) or (4), saidprocess comprises supporting a ruthenium compound on a carrier, treatingthe supported one by using a reducing compound, and oxidizing.

It is preferable that in the case of the catalyst (3) or (4), saidprocess comprises supporting a ruthenium compound on a carrier, treatingthe supported one by using an alkali solution of a reducing compound,and oxidizing.

It is preferable that the catalyst (3) or (4) is obtained by supportinga ruthenium halide on a carrier, treating the supported one by using areducing compound, and oxidizing.

It is preferable that the catalyst (3) or (4) is obtained by supportinga ruthenium halide on a carrier, treating the supported one by using analkali solution of a reducing compound, and oxidizing.

The catalyst produced by the process (5) for producing a catalyst of thepresent invention is a supported ruthenium oxide catalyst containingruthenium oxide only at an outer surface layer, not less than 80% of theouter surface of said catalyst satisfying the following expression (1):S/L<0.35  (1)wherein L is a distance between a point (A) and a point (B), said point(B) being a point formed on the surface of a catalyst when aperpendicular line dropped from any point (A) on the surface of thecatalyst to the inside of the catalyst goes out from the catalyst at theopposite side of the point (A), and S is a distance between the point(A) and a point (C), said point (C) being a point on the perpendicularline where ruthenium oxide does not exist.

Furthermore, preferably, S/L <0.30.

That is, as defined in the above formula (1), the catalyst of thepresent invention substantially contains ruthenium oxide only at anouter surface shell layer, and does not contain ruthenium oxide in theinside of the catalyst. By adopting such a structure, the activity perunit weight of ruthenium contained in the catalyst can be enhanced.

The structure of the catalyst of the present invention will be describedspecifically by using a cross sectional view of the catalyst.

The case where the catalyst has a spherical shape is as shown in FIG. 1.L corresponds to a diameter passing through a center of a sphere and Scorresponds to a thickness of an outer surface shell layer of a spherecontaining ruthenium oxide.

The case where the catalyst has a columnar shape is as shown in FIG. 2.

The case where the catalyst has a cylindrical tablet is as shown in FIG.3.

The catalyst of the present invention may have a shape other than thatdescribed above.

The process for producing the catalyst explained below is preferable toobtain a catalyst suited for the above conditions. Particularly,preferably the catalyst is prepared so as to satisfy the above formula(1) by preliminarily supporting an alkali on a carrier to be used,supporting a specific ruthenium compound, and forming a precipitate of aruthenium compound on the outer surface of the carrier by the acid-basereaction.

The process of confirming that the catalyst satisfies the above formula(1) includes a process of cutting along the plane passing through thecenter of the particles of the supported ruthenium oxide catalyst andmeasuring by using a magnifying glass having graduation, and a processof cutting in the same manner and measuring by using X-ray microanalyser(Electron probe micro analyzer) (EPMA) Since the ruthenium component isfixed to the carrier by forming a precipitate of a ruthenium compound onthe carrier and drying, the ruthenium component does not transferlargely in the step of preparing the catalyst. Therefore, the thicknessof the ruthenium oxide layer is determined by measuring the thickness ofthe layer supporting the ruthenium compound at the stage where theruthenium compound forms a precipitate on the carrier and dried.

The catalyst of the present invention is produced by supporting analkali on a carrier, supporting at least one ruthenium compound selectedfrom the group consisting of ruthenium halide, rutheniumoxy chloride,ruthenium-acetonato complex, ruthenium organic acid salt andruthenium-nitrosyl complex, treating the supported one by using areducing agent, and oxidizing. By using these steps, the activity of thecatalyst can be enhanced.

The carrier includes oxides and mixed oxides of elements, such astitanium oxide, alumina, zirconium oxide, silica, titanium mixed oxide,zirconium mixed oxide, aluminum mixed oxide, silicon mixed oxide and thelike. Preferable carriers are titanium oxide, alumina, zirconium oxideand silica, and more preferable carrier is titanium oxide. A weightratio of ruthenium oxide to the carrier is usually within a range from0.1/99.9 to 20.0/80.0, preferably from 0.5/99.5 to 15.0/85.0, and morepreferably from 1.0/99.0 to 15.0/85.0. When the proportion of theruthenium oxide is too low, the activity is lowered sometimes. On theother hand, when the proportion of ruthenium oxide is too high, theprice of the catalyst becomes high sometimes. Examples of the rutheniumoxide to be supported include ruthenium dioxide, ruthenium hydroxide andthe like.

The process of supporting ruthenium oxide on a carrier at the outersurface will be explained below. That is, the present inventors havefound that ruthenium oxide can be satisfactorily supported on a carriersuch as titanium oxide at the outer surface by using an alkalipreliminary impregnation process described below and, therefore, theexample of procedure will be explained by way of the preparationexample. That is, first, a carrier of titanium oxide having a suitableparticle diameter is impregnated with an aqueous solution of an alkalimetal hydroxide such as potassium hydroxide or an alkali such asammonium carbonate and ammonium hydrogencarbonate. In this case, athickness of a layer of a ruthenium compound at the surface to besupported on the carrier is decided by changing the kind of the alkali,concentration of the alkali, amount of ruthenium compound to besupported, and time from impregnation with ruthenium compound to drying.For example, when using potassium hydroxide, a thickness of a layer tobe impregnated with the ruthenium compound can be changed by changingthe concentration of the aqueous solution within a range from 0.1 N to2.0 N. Then, the carrier is impregnated with an aqueous solution of analkali and the carrier is dried. Then, the carrier is impregnated with asolution of ruthenium chloride. As the solution, an aqueous solution, asolution of an organic solvent such as alcohol, or a mixed solution ofwater and an organic solvent is used, but a solution of an organicsolvent such as ethanol is preferred. Then, the carrier impregnated withthe ruthenium compound is dried and hydrolyzed by using an alkali toform ruthenium hydroxide, which is converted into ruthenium oxide.Alternatively, the supported ruthenium compound is reduced to form metalruthenium, which is oxidized to form ruthenium oxide.

The alkali used preferably in the step of impregnating the carrier withan aqueous solution of an alkali includes potassium hydroxide, sodiumhydroxide, ammonium carbonate and ammonium hydrogencarbonate. Theconcentration of the alkali with which the carrier is impregnated isusually from 0.01 to 4.0 N, and preferably from 0.1 to 3.0 N. When thetime from impregnation of ruthenium compound with the carrier, which isimpregnated with the alkali, to drying is long, the inside of thecarrier is impregnated with ruthenium compound and, therefore, asuitable time must be selected according to the kind and concentrationof the alkali to be used. Usually, the support is dried immediatelyafter impregnation, or dried until 120 minutes after impregnation.Preferably, the catalyst is dried immediately after impregnation, ordried until 30 minutes after impregnation.

The ruthenium compound to be supported on the carrier include halide ofruthenium, for example, ruthenium chloride such as RuCl₃ and RuCl₃hydrate and ruthenium bromide such as RuBr₃ and RuBr₃ hydrate;rutheniumoxy chloride such as Ru₂OCl₄, Ru₂OCl₅ and Ru₂OCl₆;[Ru(CH₃COCHCOCH₃)3] ruthenium-acetylacetonato complex; ruthenium organicacid salt such as [Ru₃O(OCOCH₃)₆(H₂O)₃]OCOCH₃ hydrate andRu₂(RCOO)₄Cl(R: alkyl group having carbon atoms of 1-3); andruthenium-nitrosyl complex such as [Ru(NH₃)₅(NO)]Cl₁₃, [Ru(OH)(NH₃)₄(NO)] (NO₃)₂ and Ru(NO) (NO₃)₃. Preferable ruthenium compounds areruthenium halide, for example, ruthenium chloride such as RuCl₃ andRuCl₃ hydrate and ruthenium bromide such as RuBr₃ and RuBr₃ hydrate.More preferred one is a ruthenium chloride hydrate.

Then, the embodiment of the process for preparing a supported rutheniumoxide catalyst will be described. That is, a process of hydrolyzing asupported ruthenium by using an alkali such as aqueous solution of analkali metal hydroxide to form ruthenium hydroxide, and oxidizing toform ruthenium oxide, and a process of reducing a supported rutheniumcompound to form metal ruthenium, and oxidizing to form ruthenium oxideare exemplified. Now a process of reducing a ruthenium compound will beillustrated. The process of reducing a ruthenium compound includes aprocess of heating under a hydrogen gas flow, a process of performingwet reduction by using hydrazine, formaldehyde and sodium boron hydrideand a process of reducing by using lithium boron halide, potassium boronhalide, lithium tri-sec-butyl-boron halide, sodium tri-sec-butyl-boronhalide, potassium tri-sec-butyl-boron halide, lithium aluminum hydride,diisobutylaluminum hydride, sodium hydride and potassium hydride. Nowthe process using sodium boron hydride (NaBH₄) will be illustrated. Thatis, a ruthenium compound is supported on the above-mentioned carrier,dried and then dipped in a solution of sodium boron hydride. Thesolution includes aqueous solution, and solution of an organic solutionsuch as alcohol. A mixed solution of water and an organic solvent canalso be used. After wet reduction is conducted by using theabove-mentioned solution, the reduced one is washed with water and thendried. Then, the carrier supporting ruthenium is oxidized to formruthenium oxide. A process using an oxidizing agent and a process ofcalcining under air can be used. It is also preferable process that aprocess of impregnating a ruthenium supported one with an aqueous alkalimetal chloride solution, drying the impregnated one, and calcining underair to form ruthenium oxide. In this case, a supported ruthenium oxidecatalyst can be prepared by washing the remained alkali metal chloridewith water, and drying.

The amount of the ruthenium compound with which the carrier isimpregnated is usually the same amount as that of the rutheniumcompound, which corresponds to the already described preferable amountof ruthenium oxide to be supported.

The reducing agent used in the case of reducing the supported rutheniumcompound includes various reducing agents. When using sodium boronhydride (NaBH₄), it is preferably used in the form of a solution. Theconcentration is usually from 0.05 to 20% by weight, and preferably from0.1 to 10% by weight. A molar ratio of sodium boron hydride to thesupported ruthenium compound is usually from 1.0 to 30, and preferablyfrom 2.0 to 15.

Then, a process for preparing a supported ruthenium oxide catalyst byoxidizing the resulting supported metal ruthenium catalyst afterreduction will be illustrated. Now the process of calcining under air isillustrated. It is a preferable preparation example that the supportedmetal ruthenium is oxidized by calcining under gas containing oxygen inthe presence of an alkali metal salt to form highly active supportedruthenium oxide. As the gas containing oxygen, an air is usually used.

The calcination temperature is usually from 100 to 600° C., andpreferably from 280 to 450° C. When the calcination temperature is toolow, metal ruthenium particles are remained in a large amount and,therefore, the activity of the catalyst becomes insufficient sometimes.On the other hand, when the calcination temperature is too high,agglomeration of ruthenium oxide particles occur and, therefore, theactivity of the catalyst is lowered. The calcination time is preferablyfrom 30 minutes to 10 hours.

In this case, it is preferred to calcine in the presence of an alkalimetal salt. By using this process, it is possible to obtain higheractivity of the catalyst because that process can forming more fineparticles of ruthenium oxide comparing the process which includecalcining in the substantially absence of the alkali metal salt.

The alkali metal salt includes potassium chloride and sodium chloride.Among them, potassium chloride and sodium chloride are preferred, andpotassium chloride is more preferred.

A molar ratio of the alkali metal salt to ruthenium is preferably from0.01 to 10, and more preferably from 0.1 to 5. When the amount of thealkali metal salt to be used is too small, sufficiently highly activecatalyst is not obtained. On the other hand, when the amount of thealkali metal salt is too small, the industrial cost becomes high.

By the calcination, metal ruthenium supported on the carrier isconverted into a supported ruthenium oxide catalyst. It can be confirmedby analysis such as X-ray diffraction and XPS (X-ray photoelectronspectroscopy) that the metal ruthenium was converted into rutheniumoxide. Incidentally, substantially total amount of the metal rutheniumis preferably converted into ruthenium oxide, but the metal rutheniumcan be remained as far as the effect of the present invention is notadversely affected.

It is also possible to obtain chlorine by oxidizing hydrogen chloridewith oxygen using the catalyst of the present invention. The reactionsystem used to obtain chlorine includes, for example, flow system suchas fixed bed or fluidized bed, and a gas phase reaction such as fixedbed flow system and gas phase fluidized bed flow system can bepreferably used. The fixed bed system has an advantage that separationbetween the reaction gas and catalyst is not required and that highconversion can be accomplished because a raw gas can be sufficientlycontacted with a catalyst. The fluidized bed system has an advantagethat heat in the reactor can be sufficiently removed and temperaturedistribution width in the reactor can be minimized.

When the reaction temperature is high, volatilization of ruthenium oxidein a highly oxidized state occurs. Therefore, the reaction is preferablyconducted at low temperature and the reaction temperature is usuallyfrom 100 to 500° C., preferably from 200 to 400° C., more preferablyfrom 200 to 380° C. The reaction pressure is usually from aboutatmospheric pressure to 50 atm. As the raw material of oxygen, an airmay be used as it is, or pure oxygen may also be used. Since othercomponents are also discharged simultaneously when an inert nitrogen gasis discharged out of the plant , pure oxygen containing no inert gas ispreferable. The theoretic molar amount of oxygen based on hydrogenchloride is ¼ mol, but oxygen is usually fed in an amount that is 0.1-10times of the theoretical amount. In the case of the fixed bed gas phaseflow system, the amount of the catalyst to be used is usually from about10 to 20000 h⁻¹ in terms of a ratio (GHSV) to a feed rate of hydrogenchloride as the raw material under atmospheric pressure. GHSV means gashourly space velocity which is a ratio of a volume of feed hydrogenchloride gas (1/h) to volume of catalyst (1).

The present invention which relates to a supported ruthenium oxidecatalyst will be described below.

The supported ruthenium oxide of the present invention is a supportedruthenium oxide catalyst using titanium oxide containing not less than20% of rutile titanium oxide as a carrier. As the titanium oxide, forexample, rutile titanium oxide, anatase titanium oxide and non-crystaltitanium oxide are known. The titanium oxide containing rutile titaniumoxide used in the present invention refers to one containing a rutilecrystal by measuring a ratio of the rutile crystal to the anatasecrystal in the titanium oxide by using X-ray diffraction analysis. Themeasuring process was described in detail in this invention whichrelates to a process for producing chlorine and a process for producinga supported ruthenium oxide catalyst. When the chemical composition ofthe carrier used in the present invention is composed of titanium oxidealone, the proportion of the rutile crystal is determined from a ratioof the rutile crystal to the anatase crystal in the titanium oxide byusing X-ray diffraction analysis. In the present invention, a mixedoxide of the titanium oxide and other metal oxide is also used. In thatcase, the proportion of the rutile crystal is determined by thefollowing process. The oxide to be mixed with the titanium oxideincludes oxides of elements, and preferred examples thereof includealumina, zirconium oxide and silica. The proportion of the rutilecrystal in the mixed oxide is also determined from the ratio of therutile crystal to the anatase crystal in the titanium oxide by usingX-ray diffraction analysis, but it is necessary to contain the rutilecrystal. In this case, the content of the oxide other than the titaniumoxide in the mixed oxide is within a range from 0 to 60% by weight.Preferred carrier includes titanium oxide which does not contain a metaloxide other than titanium oxide.

The catalyst activity increases higher as the content of rutile crystalin titanium oxide becomes larger because the catalyst activity of theruthenium oxide supported on rutile crystal titanium oxide is higherthan the catalyst activity of the ruthenium oxide supported on anatasecrystal or non-crystal titanium oxide

It is necessary that the titanium oxide contains not less than 20% ofthe rutile crystal. The content of the rutile crystal is preferably notless than 30%, more preferably not less than 80%, and most preferablynot less than 90%.

The process for preparing the titanium oxide containing the rutilecrystal includes various processes and described in this invention whichrelates to a process for producing chlorine and a process for producinga supported ruthenium oxide catalyst.

The process of determining the proportion of the rutile crystal in thetitanium oxide includes a X-ray diffraction analysis. The carrier usedin the present invention is one having both of a diffraction peakintensity of the rutile crystal and a diffraction peak of the anatasecrystal. The carrier includes one wherein a proportion of the peakintensity of the rutile crystal to the total of the peak intensity ofthe rutile crystal and the peak intensity of the anatase crystal is notless than 20%, and preferably not less than 30%.

The catalyst activity can be increased by the optimization of thecontent of OH group contained in a carrier when the supported rutheniumoxide catalyst on the titanium oxide containing not less than 20% ofrutile titanium oxide is used in the oxidation reaction.

It is generally known that a hydroxyl group represented by OH bound toTi exists on the surface of the titanium oxide. The titanium oxide usedin the present invention is one containing an OH group. And the processof measuring the content of OH group was described in this inventionwhich relates to a process for producing chlorine and a process forproducing a supported ruthenium oxide catalyst. When the chemicalcomposition of the carrier used in the present invention is composed oftitanium oxide alone, it is determined from the content of the OH groupin the titanium oxide. In the present invention, a mixed oxide of thetitanium oxide and other metal oxide is also contained. The oxide to bemixed with the titanium oxide includes oxides of elements, and preferredexamples thereof include alumina, zirconium oxide and silica. In thatcase, the content of the oxide other than the titanium oxide in themixed oxide is within a range from 0 to 60% by weight. Preferred carrieris titanium oxide which does not contain the metal oxide other than thetitanium oxide.

When the content of the OH group of the carrier is large, the carrierand supported ruthenium oxide may react each other, resulting indeactivation. On the other hand, when the content of the OH group of thecarrier is small, the activity of the catalyst is lowered sometimes bysintering of the supported ruthenium oxide and the other phenomenon.

That is, in the range of the content of OH group, the catalyst activityincreases to show the peak and decreases as the content of OH groupincreases wherein the content of OH group has appropriate rangecorresponding to the amount of the ruthenium compound for supporting.Thus, the catalyst shows a high activity in the appropriate range of thecontent of OH group. The content of the OH group, which is used in thecatalyst, is usually from 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier),preferably from 0.2×10⁻⁴ to 20×10⁻⁴ (mol/g-carrier), and more preferablyfrom 3.0×10⁻⁴ to 10×10⁻⁴ (mol/g-carrier).

The process of adjusting the amount of the OH group contained in thetitanium oxide carrier to a predetermined amount was described in thisinvention which relates to a process for producing chlorine and aprocess for producing a supported ruthenium oxide catalyst.

The present invention relates to a supported ruthenium oxide catalystsupported on the above carrier, and a weight ratio of ruthenium oxide tothe carrier is usually within a range from 0.1/99.9 to 20.0/80.0,preferably from 0.5/99.5 to 15.0/85.0, and more preferably from 1.0/99.0to 15.0/85.0. When the proportion of ruthenium oxide is too low, theactivity is lowered sometimes. On the other hand, when the proportion ofruthenium oxide is too high, the price of the catalyst becomes highsometimes. Examples of the ruthenium oxide to be supported includeruthenium dioxide, ruthenium hydroxide and the like.

The process for preparing the supported ruthenium oxide catalyst byusing the above carrier includes various processes.

The process for preparing the supported ruthenium oxide catalyst of thepresent invention includes processes for preparing the catalysts (1),(2) and (3) of the invention of the process for producing chlorine.

As the ruthenium compound to be supported on a carrier, compounds listedin the catalysts (1), (2) and (3) of the invention of the process forproducing chlorine can be similarly used.

As the reducing compound used for treating the ruthenium compoundsupported on the carrier, compounds listed in the catalyst (1) of theinvention of the process for producing chlorine can be used. As thereducing hydrogenated compound, compounds listed in the catalyst (3) ofthe invention of the process for producing chlorine can be used.

It is a preferable preparation process of catalyst that the processcomprises supporting ruthenium compound on a carrier, treating by basiccompounds. The above basic compounds can be used as same as mentioned inthe catalyst (1),(2) in this invention which relates to a process forproducing chlorine.

Specific examples of the process for preparing the supported rutheniumoxide catalyst of the present invention includes process explained inthe portion in common with the catalysts (1) and (2) of the invention ofthe process for producing chlorine and process explained in the catalyst(3) of the invention of the process for producing chlorine.

It is also possible to obtain chlorine by oxidizing hydrogen chloridewith oxygen using the above-mentioned catalyst. The reaction system usedto obtain chlorine was described in this invention which relates to aprocess for producing chlorine and a process for producing a supportedruthenium oxide catalyst.

As described above, according to the present invention, there could beprovided a process for producing chlorine by oxidizing hydrogen chloridewith oxygen, wherein said process can produce chlorine by using acatalyst having high activity in a smaller amount at a lower reactiontemperature. There could also be provided a process for producingchlorine by oxidizing hydrogen chloride, wherein said process canfacilitate control of the reaction temperature by making it easy toremove the reaction heat from catalyst bed by using a catalyst havinggood thermal conductibility, which can be formed by containing acompound having high thermal conductivity of a solid phase, and canachieve high reaction conversion by keeping the whole catalyst bed atsufficient temperature for industrially desirable reaction rate.

According to the present invention, there could also be provided aprocess for producing a supported ruthenium oxide catalyst, wherein saidprocess is a process for producing a catalyst having high activity andcan produce a catalyst having high activity capable of producing thedesired compound by using a smaller amount of the catalyst at a lowerreaction temperature.

According to the present invention, there could also be provided asupported ruthenium oxide catalyst, wherein said catalyst has highactivity and can produce the desired compound by using a smaller amountof the catalyst at a lower reaction temperature.

The following Examples further illustrate the present invention indetail but are not to be construed to limit the scope thereof.

EXAMPLE 1

A catalyst was prepared by the following process. That is, 0.81 g ofcommercially available ruthenium chloride (RuCl₃.nH₂O, Ru content: 37.3%by weight) was previously dissolved in 6.4 g of pure water to prepare anaqueous solution, and 20.0 g of a titanium oxide powder (P25,manufactured by Nippon AEROSIL Co., Ltd.) was impregnated with thissolution. Then, the impregnated powder was dried at 60° C. for 2 hours.After drying, the powder was sufficiently ground in a mortar to obtain20.3 g of a dark green powder. According to the same manner as thatdescribed above, the same operation was repeated nine times to obtain183.8 g of a dark green powder.

Then, 10.4 g of this powder was dipped in a mixed solution of 2.1 g of apotassium hydroxide solution adjusted to 2N and 30.1 g of pure water ina ultrasonic cleaner at room temperature for 1 minute. In a suspensionof the dipped one and the solution, a solution of 0.61 g of a hydrazinemonohydrate and 5.0 g of pure water was poured under nitrogen at roomtemperature with applying an ultrasonic wave. At the time of pouring,bubbling was observed in the solution. After the solution was allowed tostand for 15 minutes until the bubbling disappeared, the supernatant wasseparated by filtration. 500 ml of pure water was added, followed bywashing for 30 minutes and further separation by filtration. Thisoperation was repeated five times. The pH of the wash at the first timewas 9.1, and the pH of the wash at the fifth time was 7.4. To the powderseparated by filtration, a 2 mol/l potassium chloride solution was addedand, after stirring, the powder was separated by filtration again. Thisoperation was repeated three times. The amount of the potassium chloridesolution added was 54.4 g at the first time, 52.1 g at the second timeand 52.9 g at the third time, respectively. The procedure from theoperation of dipping in the potassium hydroxide solution was repeatedsix times in the same manner to obtain 107 g of a cake. 53.1 g of theresulting cake was dried at 60° C. for 4 hours to obtain 34.1 g of agray powder. After heating from room temperature to 350° C. under airover 1 hour, the powder was calcined at the same temperature for 3hours. After the completion of the calcination, 500 ml of pure water wasadded and the mixture was stirred and, furthermore, the powder wasseparated by filtration. This operation was repeated twenty-one timesand, after adding dropwise an aqueous silver nitrate solution to thewash, it was confirmed that potassium chloride is not remained. Then,28.0 g of a bluish gray powder was obtained by drying this powder at 60°C. for 4 hours. The resulting powder was molded to adjust the particlesize to 8.6-16.0 mesh, thereby obtaining a ruthenium oxide catalystsupported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=1.9% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

X-ray diffraction analysis of the titanium oxide powder used wasconducted under the following conditions.

-   Apparatus: Rotaflex RU200B (manufactured by Rigaku Co.)-   X-ray type: Cu K α-   X-ray output: 40 kV-40 mA-   Divergence slit: 1°-   Scattering slit: 1°-   Receiving slit: 0.15 mm-   Scanning speed: 1°/min.-   Scanning speed: 5.0-75.0°-   Monochromator: curved crystal monochromator is used

The proportion of a peak intensity (381cps) of a rutile crystal(2θ=27.4°) to a total value of a peak intensity (381 cps) of a rutilecrystal (⁻) and a peak intensity (1914 cps) of an anatase crystal(2θ=25.3°) was 17%. Consequently, the content of the rutile crystal was17%.

The ruthenium oxide catalyst supported on titanium oxide (17.8 g) thusobtained was charged separately in two zones of the same glass reactiontube. The inner diameter of the glass reaction tube was 15 mm and athermocouple protective tube having an outer diameter of 6 mm wasinserted therein. In the upper zone, the catalyst was charged afterdiluting by sufficiently mixing 5.9 g of the ruthenium oxide catalystsupported on titanium oxide with 23.6 g of a commercially availablespherical (2 mm in size) α-alumina carrier (SSA995, manufactured byNikkato Co.). In the lower zone, 11.9 g of the ruthenium oxide catalystsupported on titanium oxide was charged without being diluted. Ahydrogen chloride gas (96 ml/min.) and an oxygen gas (53 ml/min.) wererespectively supplied by passing from the top to the bottom of thereactor under atmospheric pressure (in terms of 0° C., 1 atm). The upperzone of the glass reaction tube was heated in an electric furnace toadjust the internal temperature (hot spot) to 361° C. Similarly, thelower zone was heated to adjust the internal temperature (hot spot) to295° C. 4.5 Hours after the beginning of the reaction, the gas at thereaction outlet was sampled by passing it through an aqueous 30%potassium iodide solution, and then the amount of chlorine formed andamount of the non-reacted hydrogen chloride were respectively determinedby iodometric titration and neutralization titration. As a result, theconversion of hydrogen chloride was 93.0%.

According to the same reaction manner as that described above exceptthat the hydrogen chloride gas (146 ml/min.) and the oxygen gas (74ml/min.) were respectively supplied under atmospheric pressure (in termsof 0° C., 1 atm) and that the internal temperature of the upper zone wasadjusted to 360° C. and the internal temperature of the lower zone wasadjusted to 300° C., the reaction was conducted. 4.5 Hours after thebeginning of the reaction, the conversion of hydrogen chloride was91.6%.

EXAMPLE 2

A catalyst was prepared by the following process. That is, 3.52 g ofcommercially available ruthenium chloride (RuCl₃.nH₂O, Ru content: 35.5%by weight)was dissolved in 7.61 g of water, followed by sufficientstirring to obtain an aqueous ruthenium chloride solution. The resultingaqueous solution was added dropwise in 25.0 g of a spherical (1-2 mm φin size) titanium oxide carrier (CS-300S-12, anatase crystalmanufactured by Sakai Chemical Industry Co., Ltd.), thereby to supportruthenium chloride by impregnation. The supported one was dried in anair at 60° C. for 4 hours to obtain 28.0 g of a ruthenium chloridesupported on titanium oxide. 4.0 g of the resulting ruthenium chloridesupported on titanium oxide (28.0 g) was dipped in a mixed solution of2.4 g of an aqueous potassium hydroxide solution adjusted to 2 mol/l and1.2 g of pure water at room temperature for 1 minute. Then, the dippedone was poured, together with the solution, into 0.67 g of a hydrazinemonohydrate under nitrogen at room temperature. At the time of pouring,bubbling was observed in the solution. After the solution was allowed tostand for about 15 minutes until the bubbling disappeared, 4.0 g of purewater was poured, followed by stirring. Then, the supernatant wasremoved by decantation. Then, 30 ml of an aqueous potassium chloridesolution adjusted to 2 mol/l was poured and, after stirring, thesupernatant was removed by decantation. By repeating this operation sixtimes, washing with the aqueous potassium chloride solution wasconducted. Then, the washed one was dried under air at 60° C. for 4hours to obtain a spherical gray solid containing potassium chloride.

Then, the solid was heated under air from room temperature to 350° C.for about 1 hour and then calcined at the same temperature for 3 hoursto obtain a spherical solid. Washing was conducted by adding 0.5 literof pure water to the resulting solid, stirring and allowing to stand 30minutes, and the resulting solid was separated by filtration. Thisoperation was repeated four times. The washing time was about 4 hours.The washed one was dried under air at 60° C. for 4 hours to obtain 3.73g of a black spherical ruthenium oxide catalyst supported on titaniumoxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.Ru₂/(RuO₂+TiO₂)×100=6.1% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

The ruthenium oxide catalyst supported on titanium oxide (2.5 g) thusobtained was diluted by mixing with a 5 g of spherical titanium oxidecarrier (1˜2 mm φ in size) and then charged in a quartz reaction tube(inner diameter: 12 mm). A hydrogen chloride gas (192 ml/min.) and anoxygen gas (184 ml/min.) were respectively supplied under atmosphericpressure (in terms of 0° C., 1 atm). The quartz reaction tube was heatedin an electric furnace to adjust the internal temperature (hot spot) to300° C. 1.8 Hours after the beginning of the reaction, the gas at thereaction outlet was sampled by passing it through an aqueous 30 wt %potassium iodide solution, and then the amount of chlorine formed andamount of the non-reacted hydrogen chloride were respectively determinedby iodometric titration and neutralization titration.

The formation activity of chlorine per unit weight of the catalystdetermined by the following equation was 3.68×10⁻⁴ mol/min.g-catalyst.

Chlorine formation activity per unit weight of catalyst(mol/min.g-catalyst)=amount of outlet chlorine formed (mol/min)/weightof catalyst (g)

The formation activity of chlorine per unit weight of Ru determined bythe following equation was 78.4×10⁻⁴ mol/min.g-Ru.

Chlorine formation activity per unit weight of Ru (mol/min.g-Ru)=amountof outlet chlorine formed (mol/min)/weight of Ru (g)

EXAMPLE 3

A catalyst was prepared by the following process. That is, 3.52 g ofcommercially available ruthenium chloride (RuCl₃.nH₂O, Ru content: 35.5%by weight) was dissolved in 7.6 g of water, followed by sufficientstirring to obtain an aqueous ruthenium chloride solution. The resultingaqueous solution was added dropwise in 25.0 g of a spherical (1-2 mm φin size) titanium oxide carrier (CS-300S-12, manufactured by SakaiChemical Industry Co., Ltd.), thereby to support ruthenium chloride byimpregnation. The supported one was dried under air at 60° C. for 4hours to obtain 28.1 g of a ruthenium chloride supported on titaniumoxide. 4.0 g of the resulting ruthenium chloride supported on titaniumoxide (28.1 g) was dipped in a mixed solution of 2.4 g of an aqueouspotassium hydroxide solution adjusted to 2 mol/l and 1.2 g of pure waterat room temperature for 1 minute. Then, the dipped one was poured,together with the solution, into 0.67 g of a hydrazine monohydrate undernitrogen at room temperature. At the time of pouring, bubbling wasobserved in the solution. After the solution was allowed to stand forabout 15 minutes until the bubbling disappeared, 30 ml of pure water waspoured, followed by stirring. Then, the supernatant was removed bydecantation. By repeating this operation six times, washing with waterwas conducted. Then, the washed one was dried under air at 60° C. for 4hours. The dried solid was impregnated with 1.3 g of an aqueouspotassium hydroxide solution adjusted to 1.4 mol/l, and then dried underair at 60° C. for 0.5 hours to obtain a spherical gray solid containingpotassium chloride.

The calculated value of a molar ratio of potassium chloride to rutheniumwas 1.0. Then, the solid was heated under air from room temperature to350° C. for about 1 hour and then calcined at the same temperature for 3hours to obtain a spherical solid. Washing was conducted by adding 0.5 1of pure water to the resulting solid and filtering. This operation wasrepeated four times. The washing time was about 4 hours. The washed onewas dried under air at 60° C. for 4 hours to obtain 3.65 g of a blackspherical ruthenium oxide catalyst supported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.1% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

The ruthenium oxide catalyst supported on titanium oxide (2.5 g) thusobtained was charged in a quartz reaction tube (inner diameter: 12 mm)in the same manner as that described in Example 2, and then the reactionwas conducted according to the same reaction manner as that described inExample 2. 1.8 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 3.63×10⁻⁴mol/min.g-catalyst.

The formation activity of chlorine per unit weight of the Ru was77.3×10⁻⁴ mol/min.g-Ru.

EXAMPLE 4

A catalyst was prepared by the following process. That is, 50.0 g of atitanium oxide powder (STR-60N, 100% rutile crystal , manufactured bySakai Chemical Industry Co., Ltd.) was kneaded with 33.4 g of pure waterand 6.6 g of a titanium oxide sol (CSB, TiO₂ content: 38% by weight,manufactured by Sakai Chemical Industry Co., Ltd.). At room temperature,a dry air was blown to the kneaded one, which was then dried untilsuitable viscosity was obtained. The weight loss of water by drying was0.2 g. After drying, the mixture was sufficiently kneaded again. Thekneaded one was extruded into a form of a noodle of 1.5 mm φ in size.After drying under air at 60° C. for 4 hours, 46.3 g of a whitenoodle-shaped titanium oxide was obtained. After heating under air fromroom temperature to 500° C. over 1.3 hours, calcination was conducted atthe same temperature for 3 hours. After the completion of thecalcination, 45.3 g of a white extruded titanium oxide carrier wasobtained by cutting the noodle-shaped solid into pieces of about 5 mm insize. Then, 40.0 g of this carrier was impregnated with an aqueoussolution prepared by dissolving 3.23 g of commercially availableruthenium chloride (RuCl₃.nH₂O, Ru content: 37.3% by weight) in 21.9 gof pure water, and dried at 60° C. for 2 hours. Then, the resultingsolid was dipped in a solution of 16.7 g of a 2N potassium hydroxidesolution, 241 g of pure water and 4.1 g of hydrazinemonohydrate undernitrogen at room temperature, with stirring every 15 minutes. Bubblingoccurred on dipping. After 80 minutes, filtration was conducted by usinga glass filter. Washing was conducted for 30 minutes by adding 500 ml ofwater, followed by filtration. This-operation was repeated five times.The pH of the wash was 9.2 at the first time, and the pH of the wash was7.2 at the fifth time. To the extruded solid separated by filtration, 50g of a 0.5 mol/l of potassium chloride solution was added and, afterstirring, the extruded solid was separated by filtration again. Thisoperation was repeated three times. The resulting solid was dried at 60°C. for 4 hours to obtain a gray solid. After heating from roomtemperature to 350° C. in an air over 1 hour, the solid was calcined atthe same temperature for 3 hours. After the completion of thecalcination, 500 ml of pure water was added and the mixture was stirredand, furthermore, the solid was separated by filtration. This operationwas repeated ten times and, after adding dropwise an aqueous silvernitrate solution to the wash, it was confirmed that potassium chlorideis not remained. Then, 41.1 g of a bluish gray extruded ruthenium oxidecatalyst supported on titanium oxide was obtained by drying this solidat 60° C. for 4 hours.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=3.8% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=2.9% by weight

X-ray diffraction analysis of the titanium oxide powder (STR-60N) usedwas conducted under the same conditions as those of Example 1. As aresult, a peak intensity of a rutile crystal (2θ=27.40°) was 1015 cps.On the contrary a anatase crystal(2θ=25.3°) peak was not detected.Consequently, the content of the rutile crystal was 100%.

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.50 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the oxygen gas (192 ml/min.) was passedthrough the reaction tube and the internal temperature was adjusted to298° C., the reaction was conducted. 2.3 Hours after the beginning ofthe reaction, the formation activity of chlorine per unit weight of thecatalyst was 8.88×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 5

A catalyst was prepared by the following process. That is, 15.0 g of atitanium oxide powder (STR-60N, 100% rutile crystal , manufactured bySakai Chemical Industry Co., Ltd.) was dipped in an aqueous solution of2.01 g of commercially available ruthenium chloride (RuCl₃.nH₂O, Rucontent: 37.3% by weight) and 26.7 g of pure water, evaporated underreduced pressure at 50° C. for 4 hours, and then dried at 60° C. for 2hours. After drying, the powder was sufficiently ground to obtain ablack powder. This powder was dipped in a solution of 10.4 g of a 2Npotassium hydroxide solution, 69.9 of pure water and 2.53 g ofhydrazinemonohydrate undernitrogen at room temperature. Bubblingoccurred on dipping. The gas bubbled during the treatment for 1 hour wascollected and the volume was measured. As a result, it was 74 ml in anormal state. The reduced powder was separated by filtration. Washingwas conducted for 30 minutes by adding 500 ml of water, followed byfiltration. This operation was repeated five times. The pH of the washwas 9.4 at the first time, and the pH of the wash was 7.1 at the fifthtime. To the powder separated by filtration, 50 g of a 2 mol/l ofpotassium chloride solution was added and, after stirring, the powderwas separated by filtration again. This operation was repeated threetimes. The resulting cake was dried at 60° C. for 4 hours to obtain ablackish brown powder. After heating from room temperature to 350° C. inan air over 1 hour, the solid was calcined at the same temperature for 3hours. After the completion of the calcination, 500 ml of pure water wasadded and the mixture was stirred and, furthermore, the powder wasseparated by filtration. This operation was repeated five times and,after adding dropwise an aqueous silver nitrate solution to the wash, itwas confirmed that potassium chloride is not remained. Then, 14.5 g of ablack powder was obtained by drying this powder at 60° C. for 4 hours.The resulting powder was molded to adjust the particle size to 8.6-16.0mesh, thereby obtaining a ruthenium oxide catalyst supported on titaniumoxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide carrier used wasconducted under the same conditions as those of Example 1. As a result,The proportion of a peak intensity (1389cps) of a rutile crystal(2θ=27.4°) to a total value of a peak intensity (1389 cps) of a rutilecrystal and a peak intensity (40 cps) of an anatase crystal (2θ=25.3°)was 97%. Consequently, the content of the rutile crystal was 97%.

The content of the OH group of the carrier was measured in the followingmanner. That is, a sample was previously dried in an air at 150° C. for2 hours and cooled in a desiccator. Then, 1.06 g of the sample wastransferred to the flask whose atmosphere was replaced by nitrogen, andwas suspended in 40 ml of a dehydrated toluene solvent. To inhibit heatgeneration, the flask was ice-cooled and 5 ml of methyl lithium wasdropped from a dropping funnel under nitrogen. As a result, 52 ml of amethane gas was evolved. The same operation was conducted, except forusing toluene without charging no sample. As a result, 30 ml of amethane gas was evolved. At this time, the temperature was 24° C. Thecontent Q (mol/g-carrier) of the OH group was calculated by using thefollowing equation (1):Q 32 (V−V ₀)/(22400×(273+T)/273)/W  (1)where

-   V: amount of gas evolved (ml), volume of a methane gas evolved at    the temperature T during the measurement-   V₀: blank amount of gas evolved (ml), volume of a methane gas    evolved at the temperature T from remained water in the measuring    system when measuring without putting a sample-   T: Measuring temperature (° C.)-   W: Amount of sample (g)    As a result, Q was 8.5×10⁻⁴ (mol/g-carrier).

Furthermore, the valence of Ru reduced was calculated from the amount ofnitrogen produced by the hydrazine treatment according to the followingscheme (2).

As a result, the following scheme was obtained.

In the present invention, the valence of ruthenium was determined by thescheme (1).

The valence of Ru when the reaction (1) proceeds is represented by thefollowing equation:Valence number of Ru=3−((V/22400×4)/N)  (2)where V: amount of gas produced (ml), N: amount of Ru content which wascharged (mol)The valence number of Ru was calculated as 1.22.

Ru was reduced to the valence of 1.22.

On the other hand, in addition to the above reaction, there is alsoknown the reaction (3) represented by the following scheme:

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the oxygen gas (192 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 2.2 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 5.10×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 6

A catalyst was prepared by the following process. That is, 5.0 g of aspherical (1-2 mm in size) titanium oxide carrier (CS-300S-12, anatasecrystal, manufactured by Sakai Chemical Industry Co., Ltd.) wasimpregnated with a solution prepared previously by dissolving 0.71 g ofruthenium chloride (RuCl₃.nH₂O, Ru content: 35.5% by weight) in 1.7 g ofwater, and then dried at 60° C. for 2 hours. Then, a solution of 0.84 gof sodium boron hydride (NaBH₄), 4.1 g of water and 22.1 g of ethanolwas prepared. After the solution was sufficiently cooled in an ice bath,an already prepared ruthenium chloride supported on titanium carrier wasadded and ruthenium chloride was reduced. At this time, bubbling wasobserved. After the bubbling was terminated, the reduced solid wasseparated by filtration. After washing with 500 ml of pure water for 30minutes, the solid was separated by filtration. This operation wasrepeated five times. Then, this solid was dried at 60° C. for 4 hours.As a result, 5.2 g of a black solid was obtained. Then, this solid wasimpregnated with a solution prepared by dissolving 0.19 g of potassiumchloride in 3.1 g of pure water by two portions. The impregnation amountof the potassium chloride solution was 1.7 g at the first time. Afterdrying at 60° C. for 1 hour, the amount was 1.4 g at the second time.The resulting solid was dried at 60° C. for 4 hours. The dried one washeated under air to 350° C. over 1 hour and then calcined at the sametemperature for 3 hours. Then, the resulting solid was washed with 500ml of pure water for 30 minutes and then separated by filtration. Thisoperation was repeated five times. After adding dropwise an aqueoussilver nitrate solution to the filtrate, it was confirmed that potassiumchloride is not remained. After washing, the solid was dried 60° C. for4 hours to obtain 5.1 g of a spherical black ruthenium oxide catalystsupported on titanium oxide. The pore radius of the resulting catalystwas within a range from 0.004 to 0.02 micrometer. The pore distributioncurve of this catalyst measured by a mercury porosimeter is shown inFIG. 7.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂ +TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide used was conductedunder the same conditions as those of Example 1. As a result, a peak ofa rutile crystal (2θ=27.4°) was not detected to a anatase crystal peakintensity (1824 cps, 2θ=25.3°). Consequently, the content of the rutilecrystal was 0%.

Under the same conditions as those of Example 5 except that the amountof the sample was 2.56 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 86 mlof a methane gas was evolved. The content of the OH group of the carrierwas 9.0×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube and that the hydrogenchloride (187 ml/min.) and the oxygen gas (199 ml/min.) were passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 3.92×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 7

A catalyst was prepared by the following process. That is, 10.1 g of atitanium oxide powder (P25, manufactured by Nippon AEROSIL Co., Ltd.)was impregnated with an aqueous solution prepared previously bydissolving 0.41 of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) in 3.5 g of pure water, andthen dried at 60° C. for 2 hours. After drying, the powder wassufficiently ground in a mortar to obtain a dark green powder. To reducethis powder with sodium boron hydride, a solution was prepared bydissolving 0.50 g of sodium boron hydride in 100.0 g of ethanol andcooled in an ice bath. To this sodium boron hydride solution, the totalamount of ruthenium chloride supported on titanium oxide was added withstirring. Bubbling occurred on addition. After 1 hour, the supernatantwas removed by decantation. 500 ml of pure water was added, followed bywashing for 30 minutes and further separation by filtration. Thisoperation was repeated five times. The pH of the wash at the first timewas 9.3, and the pH of the wash at the fifth time was 4.2. To the powderseparated by filtration, a 2 mol/l potassium chloride solution was addedand, after stirring, the powder was separated by filtration again. Thisoperation was repeated three times. The amount of the potassium chloridesolution added was 48.1 g at the first time, 52.9 g at the second timeand 47.2 g at the third time, respectively. The resulting cake was driedat 60° C. for 4 hours to obtain a gray powder. After heating from roomtemperature to 350° C. under air over 1 hour, the powder was calcined atthe same temperature for 3 hours. After the completion of thecalcination, 500 ml of pure water was added and the mixture was stirredand, furthermore, the powder was separated by filtration. This operationwas repeated five times and, after adding dropwise an aqueous silvernitrate solution to the wash, it was confirmed that potassium chlorideis not remained. Then, 9.2 g of a bluish gray powder was obtained bydrying this powder at 60° C. for 4 hours. The resulting powder wasmolded to adjust the particle size to 8.6-16.0 mesh, thereby obtaining aruthenium oxide catalyst supported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=1.9% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube and that the hydrogenchloride (195 ml/min.) and the oxygen gas (198 ml/min.) were passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 5.56×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 8

A catalyst was prepared by the following process. That is, 10.1 g of atitanium oxide powder (P25, manufactured by Nippon AEROSIL Co., Ltd.)was impregnated with an aqueous solution prepared previously bydissolving 0.40 g of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) in 3.4 g of pure water, andthen dried at 60° C. for 2 hours. After drying, the powder wassufficiently ground in a mortar to obtain a dark green powder. Thepowder was dipped in a solution of 2.1 g of a 2N potassium hydroxidesolution and 30.2 g of pure water, and then stirred with putting a flaskin an ultrasonic cleaner. After 1 minute, a solution of 0.59 g ofhydrazine monohydrate and 5.1 g of pure water were added to thesuspension under stirring at room temperature under nitrogen. Bubblingoccurred on addition. After 15 minutes, the reduced powder was separatedby filtration. To the resulting powder, 500 ml of pure water was added,followed by washing for 30 minutes and further separation by filtration.This operation was repeated five times. The pH of the wash at the firsttime was 7.8, and the pH of the wash at the fifth time was 6.0. To thepowder separated by filtration, a 2 mol/l potassium chloride solutionwas added and, after stirring, the powder was separated by filtrationagain. This operation was repeated three times. The amount of thepotassium chloride solution added was 53.6 g at the first time, 62.4 gat the second time and 39.4 g at the third time, respectively. Theresulting cake was dried at 60° C. for 4 hours to obtain a beige powder.After heating from room temperature to 350° C. under air over 1 hour,the powder was calcined at the same temperature for 3 hours. After thecompletion of the calcination, 500 ml of pure water was added and themixture was stirred and, furthermore, the powder was separated byfiltration. This operation was repeated five times and, after addingdropwise an aqueous silver nitrate solution to the wash, it wasconfirmed that potassium chloride is not remained. Then, 8.4 g of abluish gray powder was obtained by drying this powder at 60° C. for 4hours. The resulting powder was molded to adjust the particle size to8.6-16.0 mesh, thereby obtaining a ruthenium oxide catalyst supported ontitanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=1.9% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.4% by weight

X-ray diffraction analysis of the titanium oxide powder used wasconducted under the same conditions as those of Example 1. As a result,the content of the rutile crystal was 17%.

Under the same conditions as those of Example 5 except that the amountof the sample was 4.08 g and the amount of toluene was 80 ml, thecontent of the OH group of the carrier was measured. As a result, 88 mlof a methane gas was evolved. The content of the OH group of the carrierwas 2.8×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube and that the hydrogenchloride (187 ml/min.) and the oxygen gas (199 ml/min.) were passedthrough the reaction tube and the internal temperature was adjusted to301° C., the reaction was conducted. 2.0 Hours after the beginning ofthe reaction, the formation activity of chlorine per unit weight of thecatalyst was 5.33×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 9

A catalyst was prepared by the following process. That is, 19.7 g of atitanium oxide powder (P25, manufactured by Nippon AEROSILerogyl Co.,Ltd.) was impregnated with an aqueous solution prepared previously bydissolving 0.81 g of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) in 6.0 g of pure water, andthen dried at 60° C. for 2 hours. After drying, the powder wassufficiently ground in a mortar to obtain a dark green powder. To reducethis powder with sodium boron hydride, a solution was prepared bydissolving 1.00 g of sodium boron hydride in 200 g of ethanol and cooledin an ice bath. To this sodium boron hydride solution, the total amountof ruthenium chloride supported on titanium oxide was added withstirring. Bubbling occurred on addition. After 1 hour, the supernatantwas removed by decantation. 500 ml of pure water was added, followed bywashing for 30 minutes and further separation by filtration. Thisoperation was repeated five times. The pH of the wash at the first timewas 9.8, and the pH of the wash at the fifth time was 6.6. The resultingcake was dried at 60° C. for 4 hours. As a result, 18.0 g of a bluishgray powder was obtained. Then, the resulting powder was impregnatedwith an aqueous solution of 0.66 g of potassium chloride and 9.0 g ofpure water. The resulting powder was dried at 60° C. for 4 hours. Afterheating from room temperature to 350° C. under air over 1 hour, thepowder was calcined at the same temperature for 3 hours. After thecompletion of the calcination, 500 ml of pure water was added and themixture was stirred and, furthermore, the powder was separated byfiltration. This operation was repeated five times and, after addingdropwise an aqueous silver nitrate solution to the wash, it wasconfirmed that potassium chloride is not remained. Then, 17.3 g of abluish gray powder was obtained by drying this powder at 60° C. for 4hours. The resulting powder was molded to adjust the particle size to8.6-16.0 mesh, thereby obtaining a ruthenium oxide catalyst supported ontitanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=2.0% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

X-ray diffraction analysis of the titanium oxide powder used wasconducted under the same conditions as those of Example 1. As a result,the content of the rutile crystal was 17%.

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube and that the hydrogenchloride (195 ml/min.) and the oxygen gas (198 ml/min.) were passedthrough the reaction tube and the internal temperature was adjusted to299° C., the reaction was conducted. 2.0 Hours after the beginning ofthe reaction, the formation activity of chlorine per unit weight of thecatalyst was 4.41×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 10

A catalyst was prepared by the following process. That is, a titaniumoxide powder (STR-60N, 100% rutile crystal system, manufactured by SakaiChemical Industry Co., Ltd.) was previously heated in an air from roomtemperature to 500° C. over 1.4 hours and calcined at the sametemperature for 3 hours. Then, 15.1 g of the calcined one was dipped inan aqueous solution of 0.61 g of commercially available rutheniumchloride (RuCl₃.nH₂O, Ru content: 37.3% by weight) and 26.7 g of purewater, evaporated under reduced pressure at 50° C. for 4 hours, and thendried at 60° C. for 2 hours. After drying, the powder was sufficientlyground to obtain a dark green powder. This powder was dipped in asolution of 3.2 g of a 2N potassium hydroxide solution, 52.6 of purewater and 0.77 g of hydrazine monohydrate at room temperature undernitrogen. Bubbling occurred on dipping. After 1 hour, the reduced powderwas separated by filtration. To the resulting powder, 500 ml of purewater was added, followed by washing for 30 minutes and furtherseparation by filtration. This operation was repeated seven times. ThepH of the wash was 9.9 at the first time, and the pH of the wash was 7.5at the seventh time. To the powder separated by filtration, 50 g of a 2mol/l of potassium chloride solution was added and, after stirring, thepowder was separated by filtration again. This operation was repeatedthree times. The resulting solid was dried at 60° C. for 4 hours toobtain a reddish gray powder. After heating from room temperature to350° C. under air over 1 hour, the powder was calcined at the sametemperature for 3 hours. After the completion of the calcination, 500 mlof pure water was added and the mixture was stirred and, furthermore,the powder was separated by filtration. This operation was repeated fivetimes and, after adding dropwise an aqueous silver nitrate solution tothe wash, it was confirmed that potassium chloride is not remained.Then, 13.9 g of a bluish gray powder was obtained by drying this powderat 60° C. for 4 hours. The resulting powder was molded to adjust theparticle size to 8.6-16.0 mesh, thereby obtaining a ruthenium oxidecatalyst supported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=1.9% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

Under the same conditions as those of Example 5 except that the amountof the sample was 1.31 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 48 mlof a methane gas was evolved. The content of the OH group of the carrierwas 5.6×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the oxygen gas (192 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 4.27×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 11

A catalyst was prepared by the following process. That is, a titaniumoxide powder (STR-60N, 100% rutile crystal system, manufactured by SakaiChemical Industry Co., Ltd.) was previously heated from room temperatureto 700° C. under air over 1.9 hours and calcined at the same temperaturefor 3 hours. Then, 15.0 g of the calcined one was dipped in an aqueoussolution of 0.61 g of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) and 26.7 g of pure water,evaporated under reduced pressure at 50° C. for 4 hours, and then driedat 60° C. for 2 hours. After drying, the powder was sufficiently groundto obtain a dark green powder. This powder was dipped in a solution of3.2 g of a 2N potassium hydroxide solution, 52.6 g of pure water and0.77 g of hydrazine monohydrate at room temperature under nitrogen.Bubbling occurred on dipping. After 1 hour, the reduced powder wasseparated by filtration. To the resulting powder, 500 ml of pure waterwas added, followed by washing for 30 minutes and further separation byfiltration. This operation was repeated seven times. The pH of the washwas 9.9 at the first time, and the pH of the wash was 7.5 at the seventhtime. To the powder separated by filtration, 50 g of a 2 mol/l ofpotassium chloride solution was added and, after stirring, the powderwas separated by filtration again. This operation was repeated threetimes. The resulting solid was dried at 60° C. for 4 hours to obtain agray powder. After heating from room temperature to 350° C. under airover 1 hour, the powder was calcined at the same temperature for 3hours. After the completion of the calcination, 500 ml of pure water wasadded and the mixture was stirred and, furthermore, the powder wasseparated by filtration. This operation was repeated five times and,after adding dropwise an aqueous silver nitrate solution to the wash, itwas confirmed that potassium chloride is not remained. Then, 13.5 g of abluish gray powder was obtained by drying this powder at 60° C. for 4hours. The resulting powder was molded to adjust the particle size to8.6-16.0 mesh, thereby obtaining a ruthenium oxide catalyst supported ontitanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=2.0% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

Under the same conditions as those of Example 5 except that the amountof the sample was 2.02 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 46 mlof a methane gas was evolved. The content of the OH group of the carrierwas 3.3×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the oxygen gas (192 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 4.32×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 12

A catalyst was prepared by the following process. That is, 120 of atitanium oxide powder (STR-60N, rutile crystal, manufactured by SakaiChemical Industry Co., Ltd.) was kneaded with 76.3 g of pure water and15.8 g of a titanium oxide sol (CSB, TiO₂ content: 38% by weight,manufactured by Sakai Chemical Industry Co., Ltd.). At room temperature,a dry air was blown to the kneaded one, which was then dried untilsuitable viscosity was obtained. The weight loss of water by drying was10.5 g. After drying, the mixture was sufficiently kneaded again. Thiskneaded one was extruded into a form of a noodle of 1.5 mm φ in size.After drying under air at 60° C. for 4 hours, 119 g of a whitenoodle-shaped titanium oxide was obtained. After heating under air fromroom temperature to 500° C. over 1.4 hours, calcination was conducted atthe same temperature for 3 hours. After the completion of thecalcination, 115 g of a white extruded titanium oxide was obtained bycutting the noodle-shaped solid into pieces of about 5 mm in size. Then,50.0 g of the resulting carrier was impregnated with an aqueous solutionprepared by dissolving 2.04 g of commercially available rutheniumchloride (RuCl₃.nH₂O, Ru content: 37.3% by weight) in 27.0 g of purewater, and dried at 60° C. for 2 hours. Then, the resulting solid wasdipped in a solution of 10.5 g of a 2N potassium hydroxide solution, 300g of pure water and 2.57 g of hydrazine monohydrate under nitrogen atroom temperature, followed by dipping for 1 hour with stirring every 15minutes after the reduction, filtration was conducted by using a glassfilter. Bubbling occurred on dipping. 500 ml of pure water was added,followed by washing for 30 minutes and further separation by filtration.This operation was repeated five times. The pH of the wash was 8.8 atthe first time, and the pH of the wash was 6.8 at the fifth time. To theresulting extruded solid separated by filtration, 100 g of a 0.5 mol/lof potassium chloride solution was added and, after stirring andallowing to stand 30 minutes, the resulting extruded solid was separatedby filtration again. This operation was repeated three times. Theresulting extruded solid was dried at 60° C. for 4 hours to obtain agray solid. After heating from room temperature to 350° C. under airover 1 hour, the solid was calcined at the same temperature for 3 hours.After the completion of the calcination, 500 ml of pure water was addedand the mixture was stirred and, furthermore, the solid was separated byfiltration. This operation was repeated five times over 5 hours and,after adding dropwise an aqueous silver nitrate solution to the wash, itwas confirmed that potassium chloride is not remained. Then, 50.7 g of abluish gray extruded ruthenium oxide catalyst supported on titaniumoxide was obtained by drying this resultant extruded solid at 60° C. for4 hours. Furthermore, the same operation from the impregnation step wasrepeated to obtain 50.8 g of a bluish gray extruded ruthenium oxidecatalyst supported on titanium oxide. These catalysts were mixed toobtain 101.5 g of a bluish gray extruded ruthenium oxide catalystsupported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂ (rutilcrystal)+TiO₂(binder))×100=2.0% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂(rutil crystal)+TiO₂(binder))×100=1.5% by weight

Rutil titanium oxide shows that thermal conductivity of solid phase is7.5 W/m. ° C. measured at 200° C. The calculated value of the content ofrutil titanium oxide as component (B) was as follows.TiO₂(rutil crystal)/(RuO₂+TiO₂(rutil crystal)+TiO₂(binder))×100=93.4% byweightX-ray diffraction analysis of the titanium oxide catalyst used wasconducted under the same conditions as those of Example 1. As a result,the content of the rutile crystal was 97%.

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.50 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the oxygen gas (206 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 4.83×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 13

A catalyst was prepared by the following process. That is, 10.0 g of atitanium oxide powder (MT-600B, rutile crystal system, manufactured byTAYCA Corporation ) was impregnated with an aqueous solution of 0.407 gof commercially available ruthenium chloride (RuCl₃.nH₂O, Ru content:37.3% by weight) and 17.8 g of pure water, and then evaporated underreduced pressure at 40° C. over 2 hours. After drying at 60° C. for 2hours, the powder was sufficiently ground to obtain a dark green powder.This powder was dipped in a solution of 2.1 g of a 2N potassiumhydroxide solution and 30.0 of pure water at room temperature, followedby stirring. After 1 minute, under nitrogen, a solution of 0.59 g ofhydrazine monohydrate and 5.0 g of pure water was added to thesuspension under stirring at room temperature under nitrogen. Bubblingoccurred on dipping. After 1 hour, the reduced powder was separated byfiltration. To the resulting powder, 500 ml of pure water was added,followed by washing for 30 minutes and further separation by filtration.This operation was repeated five times. The pH of the wash was 8.8 atthe first time, and the pH of the wash was 7.4 at the fifth time. To thepowder separated by filtration, 50 g of a 2 mol/l of potassium chloridesolution was added and, after stirring, the powder was separated byfiltration again. This operation was repeated three times. The resultingsolid was dried at 60° C. for 4 hours to obtain a beige powder. Afterheating from room temperature to 350° C. under air over 1 hour, thepowder was calcined at the same temperature for 3 hours. After thecompletion of the calcination, 500 ml of pure water was added and themixture was stirred and, furthermore, the powder was separated byfiltration. This operation was repeated five times and, after addingdropwise an aqueous silver nitrate solution to the wash, it wasconfirmed that potassium chloride is not remained. Then, 9.23 g of abluish gray powder was obtained by drying this powder at 60° C. for 4hours. The resulting powder was molded to adjust the particle size to8.6-16.0 mesh, thereby obtaining a ruthenium oxide catalyst supported ontitanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=2.0% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=1.5% by weight

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 5 g of acommercially available spherical (1 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the hydrogen chloride gas (211 ml/min.)and the oxygen gas (211 ml/min.) were passed through the reaction tube,the reaction was conducted. 1.8 Hours after the beginning of thereaction, the formation activity of chlorine per unit weight of thecatalyst was 4.40×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 14

A catalyst was prepared by the following process. That is, 270 g of purewater and 134 g of a 30 wt % titanium sulfate solution (manufactured byWako Pure Chemical Industry, Ltd.) were mixed at room temperature. Theresulting solution was mixed with 10.0 g of a titanium oxide powder(PT-101, 100% rutile crystal, manufactured by Ishihara TechnoCorporation ) at room temperature. Then, the resulting suspension washydrolyzed by heating to 102° C. under stirring over 7 hours using anoil bath. After the completion of the hydrolysis, the reaction solutionwas cooled to room temperature, allowed to stand overnight, and thenseparated by filtration. 0.5 liter of pure water was added to theresulting white precipitate and, after washing for 30 minutes, theprecipitate was separated by filtration. This operation was repeatedeight times. Then, the resulting precipitate was dried at 60° C. for 4hours to obtain 25.0 g of a white powder. This powder was heated to 300°C. in an air over 1 hour and then calcined at the same temperature for 5hours to obtain 23.2 g of a white solid. Furthermore, 20.2 g of thispowder was taken out, heated to 500° C. under air over 1.4 hour and thencalcined at the same temperature for 3 hours to obtain 19.5 g of a whitesolid. The resulting solid was ground to obtain a titanium oxide powder.

The resulting titanium oxide powder (9.5 g) was impregnated with anaqueous solution prepared previously by dissolving 1.27 g ofcommercially available ruthenium chloride (RuCl₃.nH₂O, Ru content: 37.3%by weight) and 9.5 g of pure water, and then evaporated under reducedpressure at 40° C. over 2 hours. After drying at 60° C. for 2 hours, thepowder was sufficiently ground to obtain a black powder. This powder wasdipped in a solution of 6.6 g of a 2N potassium hydroxide solution and28.5 g of pure water at room temperature, followed by stirring. After 1minute, a solution of 1.83 g of hydrazine monohydrate and 4.8 g of purewater was added to the suspension under stirring at room temperatureunder nitrogen. Bubbling occurred on dipping. After 1 hour, the reducedpowder was separated by filtration. To the resulting powder, 500 ml ofpure water was added, followed by washing for 30 minutes and furtherseparation by filtration. This operation was repeated five times. The pHof the wash was 8.2 at the first time, and the pH of the wash was 6.6 atthe fifth time. To the powder separated by filtration, 48 g of a 2 mol/lof potassium chloride solution was added and, after stirring, the powderwas separated by filtration again. This operation was repeated threetimes. The resulting solid was dried at 60° C. for 4 hours to obtain10.2 g of a black powder. After heating from room temperature to 350° C.in an air over 1 hour, the powder was calcined at the same temperaturefor 3 hours. After the completion of the calcination, 500 ml of purewater was added and the mixture was stirred and, furthermore, the powderwas separated by filtration. This operation was repeated five times and,after adding dropwise an aqueous silver nitrate solution to the wash, itwas confirmed that potassium chloride is not remained. Then, 8.93 g of ablack powder was obtained by drying this powder at 60° C. for 4 hours.The resulting powder was molded to adjust the particle size to 8.6-16.0mesh, thereby obtaining a ruthenium oxide catalyst supported on titaniumoxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide catalyst used wasconducted under the same conditions as those of Example 1. As a result,a peak intensity of a rutile crystal (2θ=27.4°) was1497 cps. On thecontrary a peak intensity of an anatase crystal(2θ=25.3 ) was notdetected. Consequently, the content of the rutile crystal was 100%.

Under the same conditions as those of Example 5 except that the amountof the sample was 2.36 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 51 mlof a methane gas was evolved. The content of the OH group of the carrierwas 3.7×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the hydrogen chloride gas (211 ml/min.)and the oxygen gas (211 ml/min.) were passed through the reaction tube,the reaction was conducted. 2.3 Hours after the beginning of thereaction, the formation activity of chlorine per unit weight of thecatalyst was 8.18×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 15

A catalyst was prepared by the following process. That is, a titaniumoxide powder (100% rutile crystal manufactured by Sakai ChemicalIndustry Co., Ltd.) was previously heated from room temperature to 500°C. under air over 1.4 hours and calcined at the same temperature for 3hours. Then, 10.0 g of the calcined one was dipped in an aqueoussolution of 1.34 g of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) and 17.8 g of pure water,evaporated under reduced pressure at 40° C. over 2 hours, and then driedat 60° C. for 2 hours. After drying, the powder was sufficiently groundto obtain a blackish brown powder. This powder was dipped in a solutionof 6.9 g of a 2N potassium hydroxide solution, 30.0 g of pure water and1.93 g of hydrazine monohydrate under nitrogen at room temperature.Bubbling occurred on dipping. After 1 hour, the reduced powder wasseparated by filtration. To the resulting powder, 500 ml of pure waterwas added, followed by washing for 30 minutes and further separation byfiltration. This operation was repeated five times. The pH of the washwas 8.7 at the first time, and the pH of the wash was 7.4 at the fifthtime. To the powder separated by filtration, 50 g of a 2 mol/l ofpotassium chloride solution was added and, after stirring, the powderwas separated by filtration again. This operation was repeated threetimes. The resulting solid was dried at 60° C. for 4 hours to obtain ablack powder. After heating from room temperature to 350° C. under airover 1 hour, the powder was calcined at the same temperature for 3hours. After the completion of the calcination, 500 ml of pure water wasadded and the mixture was stirred and, furthermore, the powder wasseparated by filtration. This operation was repeated five times and,after adding dropwise an aqueous silver nitrate solution to the wash, itwas confirmed that potassium chloride is not remained. Then, 9.7 g of ablack powder was obtained by drying this powder at 60° C. for 4 hours.The resulting powder was molded to adjust the particle size to 8.6-16.0mesh, thereby obtaining a ruthenium oxide catalyst supported on titaniumoxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide catalyst used wasconducted under the same conditions as those of Example 1. As a result,a peak intensity of a rutile crystal (2θ=27.4°) was 907 cps. On thecontrary, a peak intensity of an anatase crystal (2θ=25.3°) was notdetected. Consequently, the content of the rutile crystal was 100%.

Under the same conditions as those of Example 5 except that the amountof the sample was 1.64 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 54 mlof a methane gas was evolved. The content of the OH group of the carrierwas 6.0×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.5 g of the rutheniumoxide catalyst supported on titanium oxide thus obtained with 10 g of acommercially available spherical (2 mm in size) alumina carrier (SSA995,manufactured by Nikkato Co.) and then charged in a quartz reaction tube(inner diameter: 12 mm) and that the hydrogen chloride gas (211 ml/min.)and the oxygen gas (211 ml/min.) were passed through the reaction tube,the reaction was conducted. 1.8 Hours after the beginning of thereaction, the formation activity of chlorine per unit weight of thecatalyst was 7.85×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 16

A catalyst was prepared by the following process. That is, 10.1 g of atitanium oxide powder (SSP-HJ, anatase crystal, manufactured by SakaiChemical Industry Co., Ltd.) was impregnated with an aqueous solutionprepared previously by dissolving 1.35 g of commercially availableruthenium chloride (RuCl₃.nH₂O, Ru content: 37.3% by weight) in 4.5 g ofpure water, and then dried at 60° C. for 2 hours. After drying, thepowder was sufficiently ground in a mortar to obtain a black powder. Toreduce this powder with sodium boron hydride, a solution was prepared bydissolving 1.65 g of sodium boron hydride in 330 g of ethanol and cooledin an ice bath. To this sodium boron hydride solution, the total amountof ruthenium chloride supported on titanium oxide was added withstirring. Bubbling occurred on addition. After 1 hour, the supernatantwas removed by decantation. 500 ml of pure water was added, followed bywashing for 30 minutes and further separation by filtration. Thisoperation was repeated five times. The pH of the wash at the first timewas 9.3, and the pH of the wash at the fifth time was 5.3. The resultingcake was dried at 60° C. for 4 hours. As a result, 9.8 g of a blackpowder was obtained. Then, the resulting powder was impregnated with anaqueous solution of 1.21 g of potassium chloride and 4.2 g of purewater. The resulting powder was dried at 60° C. for 4 hours. Afterheating from room temperature to 350° C. under air over 1 hour, thepowder was calcined at the same temperature for 3 hours. After thecompletion of the calcination, 500 ml of pure water was added and themixture was stirred and, furthermore, the powder was separated byfiltration. This operation was repeated five times and, after addingdropwise an aqueous silver nitrate solution to the wash, it wasconfirmed that potassium chloride is not remained. Then, 9.3 g of ablack powder was obtained by drying this powder at 60° C. for 4 hours.The resulting powder was molded to adjust the particle size to 8.6-16.0mesh, thereby obtaining a ruthenium oxide catalyst supported on titaniumoxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.1% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

Under the same conditions as those of Example 5 except that the amountof the sample was 1.79 g and the amount of toluene was 40 ml, thecontent of the OH group of the carrier was measured. As a result, 111 mlof a methane gas was evolved. The content of the OH group of the carrierwas 18.6×10⁻⁴ (mol/g-carrier).

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride (187 ml/min.) and theoxygen gas (199 ml/min.) were passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was3.59×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 17

A catalyst was prepared by the following process. That is, 10.0 g of atitanium oxide powder (P25, manufactured by Nippon AEROSIL Co., Ltd.)was impregnated with an aqueous solution prepared previously bydissolving 1.34 g of commercially available ruthenium chloride(RuCl₃.nH₂O, Ru content: 37.3% by weight) in 4.8 g of pure water, andthen dried at 60° C. for 2 hours. After drying, the powder wassufficiently ground in a mortar to obtain a black powder. To reduce thispowder with sodium boron hydride, a solution was prepared by dissolving1.66 g of sodium boron hydride in 330 g of ethanol and cooled in an icebath. To this sodium boron hydride solution, the total amount ofruthenium chloride supported on titanium oxide was added with stirring.Bubbling occurred on addition. After 1 hour, the supernatant was removedby decantation. 500 ml of pure water was added, followed by washing for30 minutes and further separation by filtration. This operation wasrepeated nine times. The pH of the wash at the first time was 9.6, andthe pH of the wash at the ninth time was 7.7. The resulting cake wasdried at 60° C. for 4 hours. As a result, a black powder was obtained.Then, the resulting powder was impregnated with an aqueous solution of1.22 g of potassium chloride and 4.7 g of pure water. The impregnatedpowder was dried at 60° C. for 4 hours. After heating from roomtemperature to 350° C. under air over 1 hour, the powder was calcined atthe same temperature for 3 hours. After the completion of thecalcination, 500 ml of pure water was added and the mixture was stirredand, furthermore, the powder was separated by filtration. This operationwas repeated five times and, after adding dropwise an aqueous silvernitrate solution to the wash, it was confirmed that potassium chlorideis not remained. Then, 9.5 g of a black powder was obtained by dryingthis powder at 60° C. for 4 hours. The resulting powder was molded toadjust the particle size to 8.6-16.0 mesh, thereby obtaining a rutheniumoxide catalyst supported on titanium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide powder used wasconducted. As a result, the content of the rutile crystal was 17%.

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride (195 ml/min.) and theoxygen gas (198 ml/min.) were passed through the reaction tube and theinternal temperature was adjusted to 299° C., the reaction wasconducted. 2.0 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 4.31×10⁻⁴mol/min.g-catalyst.

EXAMPLE 18

A catalyst was prepared by the following process. That is, 60 g of acommercially available 100% rutile type titanium oxide powder (STR-60N,manufactured by Sakai Chemical Industry Co., Ltd.) and 60 g of aα-alumina powder (Al31-03, manufactured by Sumitomo Chemical Co., Ltd.)were sufficiently mixed. To the mixed one, a mixed solution of 15.8 g of38 wt % TiO₂ sol (CSB, manufactured by Sakai Chemical Industry Co.,Ltd.) and 50 g of pure water was added. Until suitable viscosity wasobtained, the mixture was dried at room temperature under air flow.After drying, the mixture was sufficiently kneaded. The weight loss bydrying was 14 g. This kneaded one was extruded into a form of a noodleof 1.5 mm φ in size, followed by drying at 60° C. under air for 4 hoursusing a drier. The weight of the dried one was 101 g. Using a mufflefurnace, the dried one was heated from room temperature to 500° C. in anair over 1.4 hours and calcined at the same temperature for 3 hours toobtain 99.5 g of a titanium oxide-α-alumina carrier.

The same operation was repeated to obtain 218 g of a titaniumoxide-α-alumina carrier.

Then, a extruded titanium oxide-α-alumina carrier was obtained bycutting the resulting noodle-shaped titanium oxide- α-alumina carrierinto pieces of about 5 mm in size.

Then, 2.03 g of commercially available ruthenium chloride (RuCl₃.nH₂O,Ru content: 37.3% by weight) was dissolved in 14.6 g of water, followedby sufficient stirring to obtain an aqueous ruthenium chloride solution.The resulting aqueous ruthenium chloride solution was added dropwise to50 g of the extruded titanium oxide-α-alumina carrier, thereby tosupport ruthenium chloride by impregnation. The supported one was driedunder air at 60° C. for 2 hours to obtain a ruthenium chloride supportedon titanium oxide-α-alumina.

The resulting ruthenium chloride supported on titanium oxide-α-aluminawas added to a mixed solution of 10.5 g of an aqueous potassiumhydroxide solution adjusted to 2 mol/l, 300 g of pure water and 2.54 gof hydrazine monohydrate under nitrogen at room temperature, followed bydipping for 1 hour stirring every 15 minutes. At the time of dipping,bubbling was observed in the solution. After the reduction, filtrationwas conducted by using a glass filter. 0.5 liter of pure water was addedto the glass filter and, after allowing to stand for 30 minutes,filtration was conducted again. This operation was repeated five timesto obtain a brownish white extruded solid. Then, 100 g of an aqueous KClsolution adjusted to 0.5 mol/l was added to the resulting extruded solidand, after allowing to stand for 30 minutes, filtration was conductedunder reduced pressure. The same operation was repeated three times.

The resulting extruded solid was dried under air at 60° C. for 4 hours,heated to 350° C. under air over 1 hour, and then calcined at the sametemperature for 3 hours.

0.5 liter of pure water was added to the calcined one and the mixturewas stirred. After allowing to stand for 30 minutes, further morefiltration was conducted by using a glass filter. This operation wasrepeated five times over 5 hours to remove potassium chloride untilwhite turbidity does not occur when 0.2 mol/l of an aqueous silvernitrate solution is added to the filtrate. Then, the resultant was driedin an air at 60° C. for 4 hours to obtain 50 g of a bluish grayruthenium oxide catalyst supported on titanium oxide-α-alumina.

The same operation was repeated four time to obtain 200 g of a rutheniumoxide catalyst supported on titanium oxide-α-alumina.

According to the same reaction manner as that described in Example 2except that 2.50 g of the ruthenium oxide catalyst supported on titaniumoxide-α-alumina thus obtained was diluted with 10 g of a commerciallyavailable spherical (2 mm in size) alumina carrier (SSA995, manufacturedby Nikkato Co.) and then charged in a quartz reaction tube (innerdiameter: 12 mm) and that the oxygen gas (192 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 4.62×10⁻⁴ mol/min.g-catalyst.

Then, the controllability of the reaction temperature of the rutheniumoxide catalyst supported on titanium oxideα-alumina was evaluated.

That is, 40.6 g of the resulting ruthenium oxide catalyst supported ontitanium oxide-α-alumina was charged in a nickel reaction tube (outerdiameter: 29 mm φ, inner diameter: 25 mmφ, outer diameter of sheath tubefor thermocouple: 6 mm φ). The length of the catalyst bed was 9.2 cm andthe volume of catalyst was 42.5 ml.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂(rutile crystal )+α-Al₂O₃+TiO₂(binder))×100=2.0% byweight

Rutil titanium oxide shows that thermal conductivity of solid phase is7.5 W/m. ° C. measured at 200° C. The calculated value of the content ofrutile titanium oxide as the component (B) was as follows.TiO₂(rutile crystal )/(RuO₂+TiO₂(rutile crystal)+α-Al₂O₃+TiO₂(binder))×100=47% by weight

α-Al₂O₃ shows that thermal conductivity of solid phase is 23 W/m. ° C.measured at 200° C. The calculated value of the content of α-alumina asthe component (B) was as follows.αAl₂O₃/(RuO₂+TiO₂(rutile crystal )+α-Al₂O₃+TiO₂(binder))×100=47% byweight

The calculated value of TiO₂(binder) used to form this catalyst was 4.7%by weight.

Then, the nickel reaction tube was heated in a salt bath of sodiumnitrite and potassium nitrate and the hydrogen chloride gas (0.88Nl/min.) and the oxygen gas (0.53 Nl/min.) were supplied. 3.7 Hoursafter the beginning of the reaction, when the temperature of the saltbath is 260° C., the maximum temperature of the catalyst bed isexhibited at the point which is 3 cm from the catalyst bed inlet and theinternal temperature (hot spot) became stable at 301° C. The gas at thereaction outlet was sampled by passing it through an aqueous 30%potassium iodide solution, and then the amount of chlorine formed andamount of the non-reacted hydrogen chloride were respectively determinedby iodometric titration and neutralization titration. As a result, theconversion of hydrogen chloride was 50.4%.

Furthermore, the bath temperature was raised by 11° C. in total over 5hours and 50 minutes to make it constant at 271° C. As a result, theinternal temperature became stable at 331.4° C. Even after 10 minutes,the bath temperature was constant at 271° C. and the internaltemperature was stable at 331.5C, and the temperature was satisfactorilycontrolled.

Furthermore, the bath temperature was raised by 8° C. in total over 1hour and 15 minutes to make it constant at 279C. As a result, theinternal temperature became stable at 351.9° C. Even after 10 minutes,the bath temperature was constant at 279 C and the internal temperaturewas stable at 351.9° C., and the temperature was satisfactorilycontrolled.

EXAMPLE 19

A catalyst was prepared by the following process. That is, 0.81 g ofcommercially available ruthenium chloride hydrate (RuCl₃.nH2O Rucontent: 37.3% by weight) was dissolved in 6.4 g of water, followed bysufficient stirring to obtain an aqueous ruthenium chloride solution.The resulting aqueous solution was added dropwise to 20 g of a titaniumoxide carrier powder (P-25, manufactured by Nippon AEROSIL Co., Ltd.),thereby to support ruthenium chloride by impregnation. The supportedruthenium chloride on titanium oxide powder was ground, and thensufficiently mixed until the whole color became homogeneous yellowishgreen. 20.2 g of a supported ruthenium chloride on titanium oxide wasobtained by dying the supported one under air at 60° C. for 2 hours. Thesame operation was repeated twice to obtain 40.4 g of the same supportedone.

Then, 40.4 g of the resulting supported ruthenium chloride on titaniumoxide was added to a mixed solution of 8.36 g of an aqueous potassiumhydroxide solution adjusted to 2 mol/l, 140 g of pure water and 2.14 gof a hydrazine monohydrate with stirring under nitrogen at roomtemperature, followed by stirring at room temperature for 60 minutes.Then, the mixed solution was filtered by using a glass filter to obtaina beige cake. 0.5 liter of pure water was added to the resulting cakeand filtration was conducted again by using a glass filter. Thisoperation was repeated five times to obtain a brownish white cake.

Then, 200 g of an aqueous KCl solution adjusted to 0.25 mol/l was addedto the resulting cake and, after allowing to stand for 30 minutes,filtration was conducted under reduced pressure. The same operation wasrepeated three times to obtain a brownish white cake. The resulting cakewas dried under air at 60° C. for 4 hours, and ground by using a mortarto obtain 39.4 g of greenish gray powder. Then, 8 g of the resultinggreenish gray powder and 8 g of α-alumina powder (AES-12, manufacturedby Sumitomo Chemical Co., Ltd.) were sufficiently mixed. To the mixedone, a mixed solution of 2.1 g of 38 wt % TiO₂ sol (CSB, manufactured bySakai Chemical Industry Co., Ltd.) and 4.0 g of pure water was added andmixed sufficiently. Until suitable viscosity is obtained, pure water wasadded, followed by kneading. The amount of pure water added is 0.45 g.The kneaded one was extruded into a form of a noodle of 1.5 mm φ insize, followed by drying at 60° C. under air for 4hours using a drier.The weight of the dried one was 5.93 g. Using a muffle furnace, thedried one was heated from room temperature to 350° C. under air over 1hour and calcined at the same temperature for 3 hours. Then, 0.5 literof pure water was added to the calcined one and filtration was conductedby using a glass filter. This operation was repeated five times toobtain a bluish gray solid. The resulting solid was dried under air at60° C. for 4 hours using a drier to obtain 5.86 g of a catalyst. Then, abluish gray extruded ruthenium oxide catalyst supported on titaniumoxide mixed with α-alumina was obtained by cutting the resulting solidinto pieces of about 5 mm in size.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂(catalyst carrier component)+α-Al₂O₃+TiO₂(binder))×100=1.0% by weight

α-Al₂O₃ shows that thermal conductivity of solid phase is 23 W/m. ° C.measured at 200° C. The calculated value of the content of α-alumina asthe component (B) was as follows.α-Al₂O₃ (component (B) )/(RuO₂+TiO₂(catalyst carriercomponent)+α-Al₂O₃+TiO₂(binder))×100=47.1% by weight

The calculated value of the content of TiO₂(binder) used to form thiscatalyst was 4.8% by weight.

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by mixing 2.50 g of the rutheniumoxide catalyst supported on titanium oxide mixed with α-alumina thusobtained with 5 g of a commercially available spherical (1 mm in size)α-alumina carrier (SSA995, manufactured by Nikkato Co.) and then chargedin a quartz reaction tube (inner diameter: 12 mm) and that the oxygengas (211 ml/min.) and hydrogen chloride gas (211 ml/min.) was passedthrough the reaction tube, the reaction was conducted. 1.8 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 3.05×10⁻⁴ mol/min.g- catalyst.

Then, the controllability of the ruthenium oxide catalyst supported ontitanium oxide mixed with α-alumina was evaluated.

That is, 5 g of the catalyst thus obtained was charged in a quartzreaction tube (outer diameter: 15 mm, inner diameter: 12 mm) withoutbeing diluted with an α-alumina sphere. The hydrogen chloride gas (192ml/min.) and the oxygen gas (192 ml/min.) were supplied. Then, thequartz reaction tube was heated in a electric furnace and the internaltemperature (hot spot) was adjusted to 300° C. 1.8 Hours after thebeginning of the reaction, the conversion of hydrogen chloride was 21%.Furthermore, the furnace temperature was slowly raised, step by step, by1° C. 5.7 Hours after the beginning of the reaction, the internaltemperature became stable at 328° C. Furthermore, the furnacetemperature was raised by 3° C. over 32 minutes. As a result, theinternal temperature became stable at 335° C., and the temperature wassatisfactorily controlled.

EXAMPLE 20

A catalyst was prepared by the following process. That is, 6.02 g of aspherical (1-2 mm in size) 5 wt % metal ruthenium catalyst supported ontitanium oxide (manufactured by N.E. Chemcat Co., Ltd. titanium oxide isanatase crystal ) was impregnated with an aqueous potassium chloridesolution adjusted to 0.5mol/l until water oozes out on the surface ofthe catalyst, and then dried under air at 60° C., for 10 to 60 minutes.This operation was repeated twice. The amount of the potassium chloridesolution added was 3.04 g at the first time, 2.89 g at the second timerespectively. The total amount was 5. 83 g. The calculated value of themolar ratio of the amount of potassium chloride added to a Ru atom inthe catalyst becomes 1:1. This solid was dried under air at 60° C. for 4hours, and heated from room temperature to 350° C. under air over about1 hour, and then calcined at the same temperature for 3 hours to obtaina spherical solid. 0.5 liter of pure water was added to the resultingsolid and the solid followed by stirring at room temperature for 1minutes. Then, the solid was filtered. This operation was repeated fourtimes until white turbidity does not occur when 0.2 mol/l of an aqueoussilver nitrate solution is added to the filtrate.

Then, the resulting solid was dried in an air at 60° C. for 4 hours toobtain 5.89 g of a bluish black 6.6 wt % ruthenium oxide catalystsupported on titanium oxide.

According to the same reaction manner as that described in Example 2except that 2.5 g of the spherical 6.6 wt % ruthenium oxide catalystsupported on titanium oxide obtained was charged in a quartz reactiontube and that the hydrogen chloride gas (187 ml/min.) and the oxygen gas(199 ml/min.) were passed through the reaction tube, the reaction wasconducted. 2.0 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 4.07×10⁻⁴mol/min.g-catalyst.

Then, 10 g of the spherical 6.6 wt % ruthenium oxide catalyst supportedon titanium oxide was prepared by the same process as described above.

Then, the mixture catalyst system which comprises the molding ofruthenium oxide catalyst supported on titanium oxide and the molding ofα-alumina was evaluated whether the catalyst system can attain enoughreaction conversion by keeping the whole catalyst bed at sufficienttemperature for desirable reaction rate in the oxidation of hydrogenchloride. That is, 9.84 g (10 ml) of the molding of the resulting 6.6 wt% ruthenium oxide catalyst supported on titanium oxide was sufficientlymixed with 65.3 g (30 ml) of α-alumina (SSA995, sphere of 2 mm in size,manufactured by Nikkato Co., Ltd.) and was charged in a quartz reactiontube (outer diameter: 25 mm φ, outer diameter of sheath tube forthermocouple : 4 mm φ). The length of catalyst bed was 11 cm.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂ (catalyst carrier component)+α-Al₂O₃)×100=0.86% byweight

α-Al₂O₃ shows that thermal conductivity of solid phase is 23 W/m. ° C.measured at 200° C. The calculated value of the content of α-alumina asthe component (B) of the catalyst system was as follows.αAl₂O₃/(RuO₂+TiO₂(catalyst carrier component )+α-Al₂O₃) ×100=86.9% byweight

Then, the quartz reaction tube was heated in a electric furnace and thehydrogen chloride gas (593 ml/min.) and the oxygen gas (300 ml/min.)were supplied. 1 Hour and 15 minutes after the beginning of the supplyof hydrogen chloride and oxygen, when the temperature of the electricfurnace was 306° C., the muximum temperature (hot spot) of the catalystbed was exhibited at the point of 4.5 cm from the catalyst bed inlet andthe internal temperature became stable at 391° C. The temperaturedistribution of the catalyst bed was as shown in FIG. 8. The gas at thereaction outlet was sampled by passing it through an aqueous 30%potassium iodide solution, and then the amount of chlorine formed andamount of the non-reacted hydrogen chloride were respectively determinedby iodometric titration and neutralization titration. As a result, theconversion of hydrogen chloride was 74.9% and the formation activity ofchlorine per unit weight of the catalyst was 14.9 molchlorine/l-catalyst system.h.

EXAMPLE 21

The controllability of the reaction temperature of the mixture catalystsystem which comprises the molding of ruthenium oxide catalyst supportedon titanium oxide and the molding of α-alumina was evaluated. That is,80.1 g of the resulting 6.6 wt % ruthenium oxide catalyst supported ontitanium oxide(anatase crystal) obtained by the same production processof example 20 was sufficiently mixed with 88.3 g of α-alumina (SSA995,sphere of 2 mm in size, manufactured by Nikkato Co., Ltd.) and wascharged in a nickel reaction tube (inner diameter: 18 mm φ, outerdiameter of sheath tube for thermocouple e: 5 mm φ). The length of thecatalyst system bed was 54 cm.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂(catalyst carrier component )+α-Al₂O₃) ×100=3.2% byweight

α-Al₂O₃ shows that thermal conductivity of solid phase is 23 W/m. ° C.measured at 200° C. The calculated value of the content of α-alumina asthe component (B) of the catalyst system was as follows.α-Al₂O₃/(RuO₂+TiO₂(catalyst carrier component )+α-Al₂O₃) ×100=52.4% byweight

Then, the nickel reaction tube was heated in a salt bath of sodiumnitrite and potassium nitrate and the hydrogen chloride gas (6.1 1/min.)and the oxygen gas (3.05 l/min.) were supplied. 1.6 Hours after thebeginning of the reaction, when the temperature of the salt bath is 280°C., the maximum temperature of the catalyst bed is exhibited at thepoint which is 10 cm from the catalyst bed inlet and the internaltemperature (hot spot) became stable at 291° C. Furthermore, the bathtemperature was raisedby 21° C. over 43 minutes to make it constant at301° C. As a result, the internal temperature became stable at 322° C.Furthermore, the bath temperature was raised by 14° C. over 1 hour and40 minutes to make it constant at 315° C. As a result, the internaltemperature became stable at 355° C. Even after 15 minutes, the bathtemperature was constant at 315° C. and the internal temperature wasstable at 355° C., and the temperature was satisfactorily controlled.

EXAMPLE 22

A catalyst was prepared by the following process. That is, 30.0 g of atitanium oxide powder (No. 1, anatase crystal, manufactured by Catalysts& Chemicals Industries Co., Ltd.) was kneaded with 9.0 g of acrystalline cellulose (manufactured by MERCK Co.), 24.4 g of a titaniumoxide sol (CSB, TiO₂ content: 38% by weight, manufactured by SakaiChemical Industry Co., Ltd.) and 25.4 g of water. The kneaded one wasdried at 60° C. and the resultant was molded into a rod-shaped solid.This rod-shaped solid was dried at 60° C. for 4 hours to obtain 48.8 gof a white solid. The resulting solid was heated to 500° C. under airover 3 hours and calcined at the same temperature for 5 hours to obtain37.1 g of a white rod-shaped titanium oxide carrier. Then, the resultingsolid was ground to obtain 27.0 g of a solid having a particle size of8.6-16 mesh.

Then, 15.0 g of the titanium oxide carrier thus obtained was taken outand impregnated with a solution prepared by dissolving 2.05 g ofcommercially available ruthenium chloride hydrate (RuCl₃.nH₂O, Rucontent: 37.3% by weight) in 9.0 g of pure water, and dried at 60° C.for 4 hours, thereby to support ruthenium chloride. 5.5 g of rutheniumchloride supported on the titanium oxide was taken out. Then, a solutionof 1.11 g of sodium boron hydride (NaBH₄), 4.0 g of water and 42.1 g ofethanol was prepared. After the solution was sufficiently cooled in anice bath, 5.5 g of the ruthenium chloride supported on titanium oxidewas added and ruthenium chloride was reduced. At this time, bubbling wasobserved in the solution. After the bubbling was terminated, the reducedsolid was separated by filtration. After washing again with 500 ml ofpure water for 30 minutes, the solid was separated by filtration. Thisoperation was repeated five times. Then, this solid was dried at 60° C.for 4 hours to obtain 5.0 g of a bluish black solid. Then, this solidwas impregnated with a solution prepared by dissolving 0.60 g ofpotassium chloride in 2.9 g of pure water, and dried at 60° C. for 4hours. The dried one was heated to 350° C. in an air over 1 hour andcalcined at the same temperature for 3 hours. Then, the calcined solidwas washed with 500 ml of pure water and then separated by filtration.This operation was repeated five times. After adding dropwise an aqueoussilver nitrate solution to the filtrate, it was confirmed that potassiumchloride is not remained. After washing, the solid was dried 60° C. for4 hours to obtain 5.1 g of a bluish black ruthenium oxide catalystsupported on titanium oxide having a particle size of 8.6-16 mesh. Thepore radius of the resulting catalyst was within a range from 0.04 to0.4 micrometer. The pore distribution curve of this catalyst measured bya mercury porosimeter is shown in FIG. 4.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.3% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.8% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride as (187 ml/min.) andthe oxygen gas (199 ml/min.) was passed through the reaction tube andthe internal temperature was adjusted to 301° C., the reaction wasconducted. 2.0 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 4.87×10⁻⁴mol/min.g-catalyst.

EXAMPLE 23

A catalyst was prepared by the following process. That is, 26.5 g of atitanium oxide powder (No. 1, manufactured by Catalysts & ChemicalsIndustries Co., Ltd.) was kneaded with 8.0 g of a fibrous cellulose(filter paper 5B, manufactured by Toyo Roshi Kaisha Ltd. ) dispersed inwater, 20.9 g of a titanium oxide sol (CSB, TiO₂ content: 38% by weight,manufactured by Sakai Chemical Industry Co., Ltd.) and water. Thekneaded one was dried at 60° C. and the resultant was molded into arod-shaped solid. This rod-shaped solid was dried at 60° C. for 4 hoursto obtain 41.1 g of a white solid. The resulting solid was heated to500° C. under air over 3 hours and calcined at the same temperature for5 hours to obtain 31.5 g of a white rod-shaped titanium oxide cattier.Then, the resulting solid was ground to obtain 20.4 g of a solid havinga particle size of 8.6-16 mesh.

Then, 5.0 g of the titanium oxide carrier thus obtained was taken outand impregnated with a solution prepared by dissolving 0.73 g ofcommercially available ruthenium chloride hydrate (RuCl₃.nH₂O, Rucontent: 35.5% by weight) in 2.8 g of pure water, and dried at 60° C.for 2 hours, thereby to support ruthenium chloride. Then, a solution of0.52 g of sodium boron hydride (NaBH₄), 2.0 g of water and 40.0 g ofethanol was prepared. After the solution was sufficiently cooled in anice bath, an already prepared ruthenium chloride supported on titaniumoxide was added and ruthenium chloride was reduced. At this time,bubbling was observed in the solution. After the bubbling wasterminated, the supernatant was separated by decantation. 200 ml ofwater was added to the reduced solid, followed by decantation. Thisoperation was repeated five times. After adding 200 ml of water, the pHwas 9.4. The pH was then adjusted to 7.1 by pouring 4.0 g of 0.1N HClinto this solution. The supernatant was removed by decantation. Afterwashing again with 500 ml of pure water for 30 minutes, the solid wasseparated by filtration. This operation was repeated five times. The pHof the filtrate at the fifth time was 7.1. Then, this solid was dried at60° C. for 4 hours to obtain 5.0 g of a bluish black solid. Then, thissolid was impregnated with a solution prepared by dissolving 0.20 g ofpotassium chloride in 2.8 g of pure water, and dried at 60° C. for 4hours. The dried one was heated to 350° C. under air over 1 hour andcalcined at the same temperature for 3 hours. Then, the calcined solidwas washed with 500 ml of pure water and then separated by filtration.This operation was repeated five times. After adding dropwise an aqueoussilver nitrate solution to the filtrate, it was confirmed that potassiumchloride is not remained. After washing, the solid was dried 60° C. for4 hours to obtain 4.9 g of a bluish black ruthenium oxide catalystsupported on titanium oxide having a particle size of 8.6-16 mesh. Thepore radius of the resulting catalyst was within a range from 0.04 to 5micrometer. The pore distribution curve of this catalyst measured by amercury porosimeter is shown in FIG. 5.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.3% by weight The calculated value of the contentof ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.8% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride as (187 ml/min.) andthe oxygen gas (199 ml/min.) was passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was4.62×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 24

A catalyst was prepared by the following process. That is, 40.3 g of atitanium oxide powder (No. 1, manufactured by Catalysts & ChemicalsIndustries Co., Ltd.) was kneaded with 12.8 g of a fibrous cellulose(filter paper 5B, manufactured by Toyo Roshi Kaisha Ltd.) dispersed inwater, 31.5 g of a titanium oxide sol (CSB, TiO₂ content: 38% by weight,manufactured by Sakai Chemical Industry Co., Ltd.) and water. Thekneaded one was dried at 60° C. and the resultant was molded into arod-shaped solid. This rod-shaped solid was dried at 60° C. for 4 hoursto obtain 64.3 g of a white solid. The resulting solid was heated to500° C. under air over 3 hours and calcined at the same temperature for5 hours to obtain 48.5 g of a white rod-shaped titanium oxide cattier.Then, the resulting solid was ground to obtain 28.0 g of a solid havinga particle size of 8.6-16 mesh.

Then, 5.1 g of the titanium oxide carrier thus obtained was taken outand was impregnated with a 0.5N potassium hydroxide solution until wateroozed out on the surface of the carrier, and then dried at 60° C. for 2hour. The impregnation amount of the aqueous potassium hydroxidesolution was 3.6 g at this times. The resulting carrier was impregnatedwith a solution prepared by dissolving 0.71 g of commercially availableruthenium chloride hydrate (RuCl₃.nH₂O, Ru content: 35.5% by weight) in3.0 g of ethanol, and immediately dried at 60° C. for 2 hours, therebyto support ruthenium chloride. Then, a solution of 0.55 g of sodiumboron hydride (NaBH₄), 2.0 g of water and 42.3 g of ethanol wasprepared. After the solution was sufficiently cooled in an ice bath, analready prepared ruthenium chloride supported on titanium oxide wasadded and ruthenium chloride was reduced. At this time, bubbling wasobserved in the solution. After the bubbling was terminated, thesupernatant was removed by decantation. 200 ml of water was added to thereduced solid, followed by decantation. This operation was repeated fivetimes. After adding 200 ml of water, the pH was 9.2. The pH was thenadjusted to 6.7 by pouring 3.6 g of 0. 1N HCl into this solution. Thesupernatant was removed by decantation. After washing again with 500 mlof pure water for 30 minutes, the solid was separated by filtration.This operation was repeated five times. Then, this solid was dried at60° C. for 4 hours to obtain 5.2 g of a bluish black solid. Then, thissolid was impregnated with a solution prepared by dissolving 0.63 g ofpotassium chloride in 3.2 g of pure water, and dried at 60° C. for 4hours. The dried one was heated to 350° C. under air over 1 hour andcalcined at the same temperature for 3 hours. Then, the calcined solidwas washed with 500 ml of pure water and then separated by filtration.This operation was repeated five times. After adding dropwise an aqueoussilver nitrate solution to the filtrate, it was confirmed that potassiumchloride is not remained. After washing, the solid was dried 60° C. for4 hours to obtain 5.1 g of a bluish black ruthenium oxide catalystsupported on titanium oxide having a particle size of 8.6-16 mesh. Thepore radius of the resulting catalyst was within a range from 0.04 to 6micrometer. The pore distribution curve of this catalyst measured by amercury porosimeter is shown in FIG. 6.

Furthermore, the thickness of the RuO₂ layer was measured by using amagnifying glass having graduation As a result, ruthenium oxide wassupported at the location which is 0.3 mm from the outer surface. Themeasured particle size of the catalyst was 1.5 mm. With respect to therange S/L wherein ruthenium oxide is supported on the surface of thecatalyst, L and S were determined as described above. As a result, thecalculated value of S/L was 0.2.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride gas (195 ml/min.) andthe oxygen gas (198 ml/min.) was passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was4.30×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 25

A catalyst was prepared by the following process. That is, 5.1 g of aspherical (1-2 mm φ in size) titanium oxide carrier (CS300S-12,manufactured by Sakai Chemical Industry Co., Ltd.) was impregnated witha 2 mol/l ammonium hydrogencarbonate solution until water oozed out onthe surface of the carrier, and then dried at 60° C. for 2 hour. Theresulting carrier was impregnated with a solution prepared by dissolving0.71 g of commercially available ruthenium chloride hydrate (RuCl₃.nH₂O,Ru content: 35.5% by weight) in 2.2 g of ethanol, and immediately driedat 60° C. for 2 hours, thereby to support ruthenium chloride. Then, asolution of 0.50 g of sodium boron hydride (NaBH₄) and 60.9 g of ethanolwas prepared. After the solution was sufficiently cooled in an ice bath,an already prepared ruthenium chloride supported on titanium oxide wasadded and ruthenium chloride was reduced. At this time, bubbling wasobserved in the solution. After the bubbling was terminated, thesupernatant was removed by decantation. 200 ml of water was added to thereduced solid, followed by decantation. This operation was repeated fivetimes. After adding 200 ml of water, the pH was 4.5. The added purewater was removed by decantation. After washing again with 500 ml ofpure water for 30 minutes, the solid was separated by filtration. Thisoperation was repeated five times. The pH of the wash at the fifth timewas 5.2. Then, this solid was dried at 60° C. for 4 hours to obtain 5.4g of a bluish black solid. Then, this solid was impregnated with asolution prepared by dissolving 0.19 g of potassium chloride in 1.9 g ofpure water, and dried at 60° C. for 4 hours. The dried one was heated to350° C. under air over 1 hour and calcined at the same temperature for 3hours. Then, the calcined solid was washed with 500 ml of pure water for30 minutes and then separated by filtration. This operation was repeatedfive times. After adding dropwise an aqueous silver nitrate solution tothe filtrate, it was confirmed that potassium chloride is not remained.After washing, the solid was dried 60° C. for 4 hours to obtain 5.4 g ofa black ruthenium oxide catalyst supported on titanium oxide.Furthermore, the thickness of the RuO₂ layer was measured by EPMA. As aresult, ruthenium oxide was supported at the location which is 0.15-0.25mm from the outer surface. The measured particle size of the catalystwas within a range from 1.4 to 1.6 mm.

The calculated value of the range S/L wherein ruthenium oxide issupported on the surface of the catalyst was within a range from 0.09 to0.18.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.1% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.6% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride as (187 ml/min.) andthe oxygen gas (199 ml/min.) was passed through the reaction tube andthe internal temperature was adjusted to 302° C., the reaction wasconducted. 2.0 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 4.47×10⁻⁴mol/min.g-catalyst.

EXAMPLE 26

A catalyst was prepared by the following process. That is, 5.0 g of aspherical (1-2 mm φ in size) titanium oxide carrier (CS300S-12,manufactured by Sakai Chemical Industry Co., Ltd.) was impregnated witha 2 mol/l ammonium carbonate solution until water oozed out on thesurface of the carrier, and then dried at 60° C. for 2 hours. Theresulting carrier was impregnated with a solution prepared by dissolving0.70 g of commercially available ruthenium chloride hydrate (RuCl₃.nH₂O,Ru content: 35.5% by weight) in 1.5 g of ethanol, and immediately driedat 60° C. for 2 hours, thereby to support ruthenium chloride. Then, asolution of 0.50 g of sodium boron hydride (NaBH₄), 2.1 g of water and41.1 g of ethanol was prepared. After the solution was sufficientlycooled in an ice bath, an already prepared ruthenium chloride supportedon titanium oxide was added and ruthenium chloride was reduced. At thistime, bubbling was observed in the solution. After the bubbling wasterminated, the supernatant was removed by decantation. 200 ml of waterwas added to the reduced solid, followed by decantation. This operationwas repeated five times. After adding 200 ml of water, the pH was 3.9.The added pure water was removed by decantation. After washing againwith 500 ml of pure water for 30 minutes, the solid was separated byfiltration. This operation was repeated five times. The pH of the washat the fifth time was 5.6. Then, this solid was dried at 60° C. for 4hours to obtain 5.3 g of a black solid. Then, this solid was impregnatedwith a solution prepared by dissolving 0.19 g of potassium chloride in1.9 g of pure water, and dried at 60° C. for 4 hours. The dried one washeated to 350° C. under air over 1 hour and calcined at the sametemperature for 3 hours. Then, the calcined solid was washed with 500 mlof pure water and then separated by filtration. This operation wasrepeated five times. After adding dropwise an aqueous silver nitratesolution to the filtrate, it was confirmed that potassium chloride isnot remained. After washing, the solid was dried 60° C. for 4 hours toobtain 5.2 g of a black ruthenium oxide catalyst supported on titaniumoxide. Furthermore, the thickness of the RuO₂ layer was measured byEPMA. As a result, ruthenium oxide was supported at the location whichis 0.19-0.30 mm from the outer surface. The measured particle size ofthe catalyst was within a range from 1.5 to 1.6 mm.

The calculated value of the range S/L wherein ruthenium oxide issupported on the surface of the catalyst was within a range from 0.13 to0.19.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride as (187 ml/min.) andthe oxygen gas (199 ml/min.) was passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was4.34×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 27

A catalyst was prepared by the following process. That is, 5.0 g of aspherical (1-2 mm φ in size) titanium oxide carrier (CS30OS-12,manufactured by Sakai Chemical Industry Co., Ltd.) was impregnated witha 2. ON potassium hydroxide solution until water oozed out on thesurface of the carrier, and then dried at 60° C. for 2 hours. Theresulting carrier was impregnated with a solution prepared by dissolving0.71 g of commercially available ruthenium chloride hydrate (RuCl₃.nH₂O,Ru content: 35.5% by weight) in 3.0 g of ethanol, and immediately driedat 60° C. for 2 hours, thereby to support ruthenium chloride. Then, asolution of 0.57 g of sodium boron hydride (NaBH₄), 2.0 g of water and42.5 g of ethanol was prepared. After the solution was sufficientlycooled in an ice bath, an already prepared ruthenium chloride supportedon titanium oxide was added and ruthenium chloride was reduced. At thistime, bubbling was observed in the solution. After the bubbling wasterminated, the supernatant was removed by decantation. 200 ml of waterwas added to the reduced solid, followed by decantation. This operationwas repeated five times. After washing again with 500 ml of pure waterfor 30minutes, the solid was separated by filtration. This operation wasrepeated five times. Then, this solid was dried at 60° C. for 4 hours toobtain 5.1 g of a black solid. Then, this solid was impregnated with asolution prepared by dissolving 0.19 g of potassium chloride in 1.8 g ofpure water, and dried at 60° C. for 4 hours. The dried one was heated to350° C. under air over 1 hour and calcined at the same temperature for 3hours. Then, the calcined solid was washed with 500 ml of pure water for30 minutes and then separated by filtration. This operation was repeatedfive times. After adding dropwise an aqueous silver nitrate solution tothe filtrate, it was confirmed that potassium chloride is not remained.After washing, the solid was dried 60° C. for 4 hours to obtain 5.1 g ofa black ruthenium oxide catalyst supported on titanium oxide.Furthermore, the thickness of the RuO₂ layer was measured by EPMA. As aresult, ruthenium oxide was supported at the location which is 0.11-0.18mm from the outer surface. The measured particle size of the catalystwas within a range from 1.5 to 1.7 mm.

The calculated value of the range S/L wherein ruthenium oxide issupported on the surface of the catalyst was within a range from 0.06 to0.11.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in a reaction tube in the same manner asthat in Example 2 and that the hydrogen chloride as (187 ml/min.) andthe oxygen gas (199 ml/min.) was passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was4.29×10⁻⁴ mol/min.g-catalyst.

EXAMPLE 28

A catalyst was prepared by the following process. That is, 122 g ofchromium nitrate enneahydrate was dissolved in 600 ml of pure water andthe solution was heated to 42° C. Then, 130 g of 25 wt % ammonia waterwas added dropwise over 2 hours with stirring, followed by stirring atthe same temperature for additional 30 minutes. The formed precipitatewas separate by filtration under reduced pressure. 1 liter of water wasadded to the formed precipitate, followed by stirring and furtherfiltration under reduced pressure. After the precipitate was washed byrepeating this operation five times, and then dried at 60° C. to obtaina bluish green solid. The resulting bluish green solid was ground, andheated under air from room temperature to 375° C. over 1 hour, and thencalcined at the same temperature for 3 hours to obtain 23.5 g of a blackchromium oxide powder.

Then, 0.89 g of commercially available ruthenium chloride hydrate(RuCl₃.nH₂O, Ru content: 35.5% by weight) was dissolved in 2.16 g ofpure water to obtain an aqueous ruthenium chloride solution. 1.64 g ofthe resulting aqueous solution was added dropwise until the pores of the6.0 g of chromium oxide are nearly impregnated with the aqueoussolution, followed by drying at 60° C. Then, 1.40 g of the remainingaqueous ruthenium chloride solution was added dropwise to the chromiumoxide carrier, thereby to support the total amount of ruthenium chlorideby impregnation to obtain a black powder. The resulting black powder wasdried in an air at 60° C., heated under air from room temperature to350° C. over 1 hour, and then calcined at the same temperature for 3hours to obtain 6.3 g of a black powder. The resulting powder was moldedto adjust the particle size to 12-18.5 mesh, thereby to obtain acalcined catalyst of ruthenium chloride supported on chromium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.5% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.9% by weightAccording to the same reaction manner as that described in Example 2except that the catalyst was diluted by sufficiently mixing 2.5 g of thecalcined ruthenium chloride supported on chromium oxide thus obtainedwith 5 g of a titanium oxide carrier adjusted to 12-18.5 mesh and thencharged in a quartz reaction tube (inner diameter: 12 mm) and that thehydrogen chloride gas (200 ml/min.) and the oxygen gas (200 ml/min.)were passed through the reaction tube and the internal-temperature wasadjusted to 301° C., the reaction was conducted. 2.2 Hours after thebeginning of the reaction, the formation activity of chlorine per unitweight of the catalyst was 6.1×10⁻⁴ mol/min.g-catalyst. The formationactivity of chlorine per unit weight of Ru was 124×10⁻⁴mol/min.g-catalyst.

EXAMPLE 29

A catalyst was prepared by the following process. That is, 1.10 g ofcommercially available ruthenium chloride hydrate (RuCl₃.nH₂O, Rucontent: 35.5% by weight) was dissolved in 1000 ml of an aqueous 0.1mol/l hydrochloric acid solution, and the solution was allowed to standfor 30 minutes. Then, 7.5 g of the chromium oxide powder obtained inExample 30 was suspended in this solution and the pH was adjusted to 4.5by adding an aqueous 0.1 mol/l potassium hydroxide solution withstirring, thereby precipitation -supporting ruthenium on chromium oxideThen, this suspension was heated to 60° C. with adjusting the pH to 4.5,and then stirred for 5 hours. After the completion of stirring, thesuspension was air-cooled to not more than 40° C., filtered underreduced pressure, and then dried at 60° C. to obtain a solid. The solidwas ground, heated under air from room temperature to 70° C. over 1hour, and then calcined at the same temperature for 8 hours. Thecalcined one was heated under air from room temperature to 375° C. over1 hour, and then calcined at the same temperature for 8 hours. 7.6 g ofthe resulting black powder was washed with 0.5 liter of pure water tentimes over 1 day, and then dried under air at 60° C. over 8 hours toobtain 7.1 g of a black powder. The resulting powder was molded toadjust the particle size to 12-18.5 mesh, thereby to obtain a catalystof ruthenium oxide supported on chromium oxide.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+Cr₂O₃)×100=6.4% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+Cr₂O₃)×100=4.9% by weight

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by sufficiently mixing 2.5 g of theruthenium oxide supported on chromium oxide thus obtained with 5 g of atitanium oxide carrier adjusted to 12-18.5 mesh and then charged in aquartz reaction tube (inner diameter: 12 mm) and that the hydrogenchloride gas (187 ml/min.) and the oxygen gas (194 ml/min.) were passedthrough the reaction tube, the reaction was conducted. 2.0 Hours afterthe beginning of the reaction, the formation activity of chlorine perunit weight of the catalyst was 4.75×10⁻⁴ mol/min.g-catalyst. Theformation activity of chlorine per unit weight of Ru was 97.6×10⁻⁴mol/min.g-catalyst.

COMPARATIVE EXAMPLE 1

A catalyst was prepared by the following process. That is, 0.70 g of acommercially available ruthenium chloride hydrate (RuCl₃.3H₂0, Rucontent: 35.5%) was dissolved in 4.0 g of water. After the aqueoussolution was sufficiently stirred, 5.0 g of silica (Cariact G-10,manufactured by Fuji Silysia Chemical Co., Ltd.) obtained by adjusting aparticle size to 12 to 18.5 mesh and drying under air at 500° C. for 1hour, was impregnated with the solution of ruthenium chloride dropwise,thereby to support ruthenium chloride by impregnation. The supported onewas heated from room temperature to 100° C. under a nitrogen flow (100ml/min.) over 30 minutes, dried at the same temperature for 2 hours, andthen air-cooled to room temperature to obtain a black solid. Theresulting solid was heated from room temperature to 250° C. over 1 hourand 30 minutes under an air flow of 100 ml/min., dried at the sametemperature for 3 hours and then air-cooled to room temperature toobtain 5.37 g of black ruthenium chloride catalyst supported on silica.Incidentally, the calculated value of the content of ruthenium was asfollows.Ru/(RuCl_(3.3)H₂O+SiO₂)×100=4.5% by weight

According to the same manner as that described in Example 2 except that2.5 g of the ruthenium chloride catalyst supported on silica thusobtained was charged in a reaction tube without being diluted with atitanium oxide carrier in the same manner as that in Example 2 and thatthe hydrogen chloride gas (202 ml/min.) and the oxygen gas (213 ml/min.)were passed through the reaction tube and the internal temperature wasadjusted to 300° C., the reaction was conducted. 1.7 Hours after thebeginning of the reaction, the formation activity of chlorine per unitweight of the catalyst was 0.49×10⁻⁴ mol/min.g-catalyst.

COMPARATIVE EXAMPLE 2

A catalyst was prepared by the following process. That is, 8.0 g of apowder obtained by grinding a spherical titanium oxide (CS-300,manufactured by Sakai Chemical Industry Co., Ltd.) in a mortar wassufficiently mixed with 0.53 g of a ruthenium dioxide powder(manufactured by NE Chemcat Co., Ltd.) with grinding in a mortar, andthen molded to adjust the particle size to 12-18.5 mesh, thereby toobtain a ruthenium oxide-titanium oxide mixed catalyst. Incidentally,the calculated value of the content of ruthenium oxide was 6.2% byweight. The calculated value of the content of ruthenium was 4.7% byweight.

According to the same manner as that described in Example 2 except that2.5 g of the ruthenium oxide- titanium oxide mixed catalyst thusobtained was charged in the reaction tube in the same manner as that inExample 2 and that the hydrogen chloride gas (199 ml/min.) and theoxygen gas (194 ml/min.) were passed through the reaction tube and theinternal temperature was adjusted to 299° C., the reaction wasconducted. 2.3 Hours after the beginning of the reaction, the formationactivity of chlorine per unit weight of the catalyst was 0.83×10⁻⁴mol/min.g-catalyst.

COMPARATIVE EXAMPLE 3

A catalyst was prepared by the following process. That is, 41.7 g ofcommercially available tetraethyl orthosilicate was dissolved in 186 mlof ethanol and 56.8 g of titanium tetraisopropoxide was poured into thesolution. After stirring at room temperature for 30 minutes, an aqueoussolution which is obtained by sufficiently mixing an aqueous 0.01 mol/lacetic acid solution, prepared by dissolving 0.14 g of acetic acid in233 ml of pure water, with 93 ml of ethanol was added dropwise. As thesolution added dropwise, a white precipitate was produced. After thecompletion of the dropwise addition, the solution was stirred at roomtemperature for 1 hour, heated with stirring and then refluxed on an oilbath at 102° C. for 1 hour. The temperature of the solution at this timewas 80° C. This solution was air-cooled, filtered with a glass filer,washed with 500 ml of pure water and then filtered again. After thisoperation was repeated twice, the resultant was dried under air at 60°C. for 4 hour, heated from room temperature to 550° C. for 1.5 hour andthen calcined at the same temperature for 3 hours to obtain 27.4 g of awhite solid. The resulting solid was ground to obtain a titania silicapowder.

The resulting titania silica powder (8.0 g) was impregnated with asolution prepared by dissolving 1.13 g of a commercially availableruthenium chloride hydrate (RuCl₃.nH₂O, Ru content: 35.5%) in 8.2 g ofwater, followed by drying in air at 60° C. for 1 hour to supportruthenium chloride. The supported one was heated from room temperatureto 300° C. under a mixed flow of hydrogen (50 ml/min.) and nitrogen (100ml/min.) over 1.5 hour, reduced at the same temperature for 1 hour andthen air-cooled to room temperature to obtain 8.4 g of a grayish brownmetal ruthenium supported on titania silica powder.

The resulting metal ruthenium supported on titania silica powder (8.4 g)was heated from room temperature to 600° C. under air flow over 3 hoursand 20 minutes and then calcined at the same temperature for 3 hours toobtain 8.5 g of a gray powder. The resulting powder was molded to adjustthe particle size to 12 to 18.5 mesh, thereby to obtain a rutheniumoxide catalyst supported on titania silica.

Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂+SiO₂)×100=6.2% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂+SiO₂)×100=4.7% by weight

According to the same reaction manner as that described in Example 2except that the ruthenium oxide catalyst supported on titania silica(2.5 g) thus obtained was charged in a reaction tube without dilutingwith the titanium oxide carrier in the same manner as that described inExample 2 and that the hydrogen chloride gas (180 ml/min.) and theoxygen gas (180 ml/min.) were passed through the reaction tube, thereaction was conducted. 1.8 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was0.46×10⁻⁴ mol/min.g-catalyst.

COMPARATIVE EXAMPLE 4

A catalyst was prepared by the following process. That is, 60.3 g ofchromium nitrate enneahydrate was dissolved in 600 ml of water and thesolution was heated to 45° C. Then, 64.9 g of 25 wt % ammonia water wasadded dropwise over 1.5 hours with stirring, followed by stirring at thesame temperature for additional 30 minutes. 3.3 liter of water was addedto the formed precipitate and, after allowing to stand overnight tocause sedimentation, the supernatant was removed by decantation. Then,2.7 liter of water was added, followed by stirring sufficiently for 30minutes. The precipitate was washed by repeating this operation fivetimes. After the precipitate was washed, the supernatant was removed bydecantation. Then, 49 g of 20 wt % silica sol was added and, afterstirring, the mixture was evaporated to dryness at 60° C. using a rotaryevaporator. The resultant was dried at 60° C. for 8 hours and then driedat 120° C. for 6 hours to obtain a green solid. Then, this solid wascalcined in air at 600° C. for 3 hours and then molded to obtain aCr₂O₃-SiO₂ catalyst of 12.5 to 18 mesh.

According to the same reaction manner as that described in Example 2except that 2.5 g of the Cr₂O₃-SiO₂ catalyst thus obtained was chargedin the reaction tube without being diluted with a titanium oxide carrierin the same manner as that described in Example 2 and that the oxygengas (200 ml/min.) was passed through the reaction tube and the internaltemperature was adjusted to 301° C., the reaction was conducted. 3.7Hours after the beginning of the reaction, the formation activity ofchlorine per unit weight of the catalyst was 0.19×10⁻⁴mol/min.g-catalyst.

COMPARATIVE EXAMPLE 5

A catalyst was prepared by the following process. That is, 10.1 g of aspherical (1-2 mm in size) titanium oxide carrier (CS-300S-12,manufactured by Sakai Chemical Industry Co., Ltd.) was impregnated witha solution prepared previously by dissolving 1.34 g of commerciallyavailable ruthenium chloride (RuCl₃.nH₂O, Ru content: 37.3% by weight)in 3.7 g of pure water, and then dried at 60° C. for 4 hours. As aresult, a blackish brown solid was obtained. To reduce this solid withhydrogen, the solid was heated from room temperature to 250° C. under amixed gas flow of hydrogen (20 ml/min.) and nitrogen (200 ml/min.) over2 hours, and then reduced at the same temperature for 8 hours. After thereduction, 10.3 g of a black solid was obtained. Then, the resultingsolid was heated to 350° C. under air over 1 hour, and then calcined atthe same temperature for 3 hours. As a result, 10.6 g of a blackruthenium oxide catalyst supported on titanium oxide was obtained.Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.1% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=4.7% by weight

X-ray diffraction analysis of the titanium oxide used was conductedunder the same conditions as those of Example 1. As a result, thecontent of the rutile crystal was 0%.

According to the same reaction manner as that described in Example 2except that 2.5 g of the ruthenium oxide catalyst supported on titaniumoxide thus obtained was charged in the reaction tube in the same manneras that described in Example 2 and that the hydrogen chloride (187ml/min.) and the oxygen gas (199 ml/min.) were passed through thereaction tube, the reaction was conducted. 2.0 Hours after the beginningof the reaction, the formation activity of chlorine per unit weight ofthe catalyst was 2.89×10⁻⁴ mol/min.g-catalyst.

COMPARATIVE EXAMPLE 6

A catalyst was prepared by the following process. That is, 10.0 g of aspherical (1-2 mm in size) 5 wt % supported metal ruthenium-titaniumoxide catalyst (manufactured by N.E. Chemcat Co., Ltd.) was impregnatedwith an aqueous 0.5 mol/l of potassium chloride solution until wateroozed out on the surface of the catalyst, and then dried at 60° C. for 1hour. This operation was repeated twice. The impregnation amount of theaqueous potassium chloride solution was 3.31 g at the first time, and3.24 g at the second time. The total amount was 6.55 g. The calculatedvalue of the molar ratio of potassium chloride to ruthenium was 0.66.Then, the resulting solid was dried. The dried one was heated to 350° C.under air over 1 hour, and then calcined at the same temperature for 3hours. Then, the resulting solid was washed with 500 ml of pure waterfor 30 minutes and filtered off. This operation was repeated five times.An aqueus silver nitrate solution was added dropwise to the filtrate andit was confirmed that potassium chloride is not remained. After washing,the solid was dried at 60° C. for 4 hours to obtain 9.9 g of a sphericalblack ruthenium oxide catalyst supported on titanium oxide.Incidentally, the calculated value of the content of ruthenium oxide wasas follows.RuO₂/(RuO₂+TiO₂)×100=6.6% by weight

The calculated value of the content of ruthenium was as follows.Ru/(RuO₂+TiO₂)×100=5.0% by weight

According to the same reaction manner as that described in Example 2except that the catalyst was diluted by sufficiently mixing 2.5 g of theruthenium oxide catalyst supported on titanium oxide thus obtained withtitanium oxide carrier and then charged in a quartz reaction tube (innerdiameter: 12 mm) and that the hydrogen chloride (187 ml/min.) and theoxygen gas (199 ml/min.) were passed through the reaction tube, thereaction was conducted. 2.0 Hours after the beginning of the reaction,the formation activity of chlorine per unit weight of the catalyst was4.03×10⁻⁴ mol/min.g-catalyst.

COMPARATIVE EXAMPLE 7

40.1 g of a 6.6 wt % ruthenium oxide catalyst supported on titaniumoxide (anatase crystal) obtained in the same manner as that described inExample 20 was charged in the same reaction tube as that in Example 18,and then heated in the same salt bath. The length of the catalyst bedwas 9.2 cm.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was 6.6% by weight.

According to the method for evaluation of the controllability of thereaction temperature of Example 18, the reaction was conducted. Thehydrogen chloride gas (0.881/min.) and the oxygen gas (0.53 1/min.) weresupplied. 5.5 Hours after the beginning of the reaction, the bathtemperature became constant at 276° C. and the internal temperature (hotspot) became stable at 301.5° C. The conversion of hydrogen chloride atthis time was 37%. Even after 50 minutes, the bath temperature wasconstant at 277° C. and the internal temperature was stable at 302.3° C.Then, the bath temperature was raised by 4° C. in total over 55 minutesto make it constant at 281° C. As a result, the internal temperatureraised to 348° C. and it became difficult to control the reactiontemperature. At the time when the internal temperature raised to 348°C., supply of the reaction gas was stopped and the reaction operationended.

COMPARATIVE EXAMPLE 8

According to the same manner as that described in Example 20 except forusing 65.3 g (51 ml) of a high purity quartz ball (quartz glass (thermalconductivity of a solid phase at 227° C. is 1.6 W/m. ° C.) sphere of 2mm in size, manufactured by Nikkato Co.) wherein purity of SiO₂ is notless than 99.99% in place of α-alumina, a catalyst system was obtained.The length of the catalyst bed in the same reaction tube as that inExample 20 was 16.5 cm.

Incidentally, the calculated value of the content of ruthenium oxide asthe active component (A) of the catalyst was as follows.RuO₂/(RuO₂+TiO₂(catalyst carrier component )+SiO₂) ×100=0.86% by weight

Quartz glass used is not a component (B) because thermal conductivity ofa solid phase at 227° C. is 1.6W/m. ° C.

According to the same manner as that described in Example 22 except thatthe temperature of the electric furnace was controlled so that themaximum temperature (hot spot) of the catalyst bed becomes the sametemperature as that in Example 22, the reaction was conducted.

1 Hour and 15 minutes after the beginning of the supply of hydrogenchloride and oxygen, the temperature of the electric furnace becameconstant at 297° C. and the maximum temperature (hot spot) of thecatalyst bed became stable at 390° C. at the point which is 4 cm fromthe catalyst bed inlet and, furthermore, the temperature distribution ofthe catalyst bed was as shown in FIG. 9. According to the same manner asthat described in Example 20, the formation amount of chlorine and theamount of the non-reacted hydrogen chloride were measured. As a result,the conversion of hydrogen chloride was 62.3% and the formationefficiency of chlorine was 8.1 mol chlorine/l-catalyst system.h.(Results are summarized in the Table.) TABLE Formation TemperatureConversion efficiency of catalyst of hydrogen of chlorine²⁾ bed(° C.)chloride¹⁾ (mol chlorine/ (hot spot) (%) catalyst system · h) Example 20391 74.9 14.9 comparative 390 62.3 8.1 Example 8¹⁾Conversion of hydrogen chloride = ((mol formed chlorine per unit time× 2)/(mol supplied chlorine per unit time)) × 100²⁾Formation efficiency of chlorine = (mol formed chlorine per unittime)/(volume of charged catalyst system)

COMPARATIVE EXAMPLE 9

121 g of a 6.6 wt % ruthenium oxide catalyst supported on titanium oxideobtained in the same manner as that described in Example 20 was chargedin the same reaction tube as that in Example 21, and then heated in thesame salt bath. The length of the catalyst bed was 54 cm. Incidentally,the calculated value of the content of ruthenium oxide as the activecomponent (A) of the catalyst was 6.6% by weight. According to the samemethod for evaluation of the controllability of the reaction temperatureof Example 21, the reaction was conducted. The hydrogen.) chloride gas(6.1 l/min.) and the oxygen gas (3.05 l/min.) where supplied.

8.4 Hours after the beginning of the reaction, the bath temperaturebecame constant at 295.5° C. and the internal temperature (hot spot)became estable at 330° C. Then, the bath temperature was raiced by 5.5°C. in total over 23 minutes to make it constant at 301° C. As a result,the internal temperature raised to 350° C. and it became difficult tocontrol the reaction temperature. At the time when the internaltemperature raised to 350° C., supply of the reaction gas was stooppedand the reaction operation ended.

1. A process for producing chlorine by oxidizing hydrogen chloride withoxygen, wherein said process uses one catalyst selected from thefollowing catalysts (1) to (9): (1) a supported ruthenium oxide catalystobtained by the steps which comprise supporting a ruthenium compound ona carrier, treating the supported one by using a basic compound,treating by using a reducing compound, and oxidizing; (2) a supportedruthenium oxide catalyst obtained by the steps which comprise supportinga ruthenium compound on a carrier, treating the supported one by using areducing agent to form ruthenium having an oxidation number of 1 to lessthan 4 valence, and oxidizing; (3) a supported ruthenium oxide catalystobtained by the steps which comprise supporting a ruthenium compound ona carrier, reducing the supported one by using a reducing hydrogenatedcompound, and oxidizing; (4) a supported ruthenium oxide catalystobtained by using titanium oxide containing rutile titanium oxide as acarrier; (5) a supported ruthenium oxide catalyst obtained by the stepswhich comprise supporting a ruthenium compound on a carrier, treatingthe supported one by using a reducing compound or reducing agent in aliquid phase, and oxidizing, wherein titanium oxide contains an OH groupin an amount of 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier) per unit weight ofthe carrier; (6) a catalyst system containing the following component(A), and not less than 10% by weight of component (B): (A) an activecomponent of catalyst; (B) a compound wherein thermal conductivity of asolid phase measured by at least one point within a range from 200 to500° C. is not less than 4 W/m. ° C.; (7) a supported ruthenium oxidecatalyst having a macro pore with a pore radius of 0.03 to 8 micrometer;(8) an outer surface-supported catalyst obtained by supporting rutheniumoxide on a carrier at the outer surface; and (9) a supported rutheniumcatalyst obtained by using chromium oxide as a carrier.
 2. The processaccording to claim 1 (1), wherein the reducing compound is a compoundselected from the group consisting of hydrazine, methanol, ethanol,formaldehyde, hydroxylamine, formic acid and compounds having aoxidation-reduction potential of −0.8 to 0.5 V.
 3. The process accordingto claim 1, wherein the catalyst (2) is a supported ruthenium oxidecatalyst obtained by the steps which comprise supporting at least oneruthenium compound selected from the group consisting of rutheniumhalide, chlororuthenate salt, oxyruthenate salt, rutheniumoxy chloride,ruthenium-ammine complex, chloride of ruthenium-ammine complex,ruthenium acetylacetonato complex, ruthenium organic acid salt andruthenium-nitrosyl complex on a carrier, treating the supported one byusing a reducing agent to form ruthenium having an oxidation number of 1to less than 4 valence, and oxidizing.
 4. The process according to claim1, wherein the catalyst (2) is a supported ruthenium oxide catalystobtained by the steps which comprise supporting at least one rutheniumcompound selected from the group consisting of ruthenium halide,chlororuthenate salt, oxyruthenate salt, rutheniumoxy chloride,ruthenium-ammine complex, chloride of ruthenium-ammine complex,ruthenium acetylacetonato complex, ruthenium organic acid salt andruthenium-nitrosyl complex on a carrier, treating the supported one byusing a basic compound, treating by using a reducing agent, andoxidizing.
 5. The process according to claim 1 (2), wherein the reducingagent is a reducing compound.
 6. The process according to claim 1,wherein the catalyst (1) or (2) is a supported ruthenium oxide catalystobtained by supporting ruthenium halide on a carrier, treating thesupported one by using hydrazine, methanol, ethanol or formaldehyde, andoxidizing.
 7. The process according to claim 1, wherein the catalyst (1)or (2) is a supported ruthenium oxide catalyst obtained by supporting aruthenium compound on a carrier, treating the supported one by using analkali solution of hydrazine, methanol, ethanol or formaldehyde, andoxidizing.
 8. The process according to claim 1, wherein the catalyst (1)or (2) is a supported ruthenium oxide catalyst obtained by supporting aruthenium compound on a carrier, treating the supported one by using analkali, treating by using a reducing compound, and oxidizing.
 9. Theprocess according to claim 1, wherein the catalyst (1) or (2) is asupported ruthenium oxide catalyst prepared by supporting a rutheniumcompound on a carrier, treating the supported one by using an alkalisolution of a reducing compound, and oxidizing.
 10. The processaccording to claim 1, wherein the catalyst (1) or (2) is a supportedruthenium oxide catalyst obtained by supporting ruthenium halide on acarrier, treating the supported one by using an alkali, treating byusing hydrazine, methanol, ethanol or formaldehyde, and oxidizing. 11.The process according to claim 1, wherein the catalyst (1) or (2) is asupported ruthenium oxide catalyst obtained by supporting rutheniumhalide on a carrier, treating the supported one by using an alkalisolution of hydrazine, methanol, ethanol or formaldehyde, and oxidizing.12. The process according to claim 1, wherein the catalyst (1) or (2) isa supported ruthenium oxide catalyst obtained by supporting rutheniumhalide on a carrier, treating the supported one by adding an alkali,treating by using hydrazine, and oxidizing.
 13. The process according toclaim 1, wherein the catalyst (1) or (2) is a supported ruthenium oxidecatalyst obtained by supporting ruthenium halide on a carrier, treatingthe supported one by using an alkali solution of hydrazine, andoxidizing.
 14. The process according to claim 1, wherein the catalyst(1) or (2) is a supported ruthenium oxide catalyst obtained bysupporting ruthenium halide on a carrier, treating the supported one byadding an alkali, treating with hydrazine, adding an alkali metalchloride, and oxidizing.
 15. The process according to claim 1, whereinthe catalyst (1) or (2) is a supported ruthenium oxide catalyst obtainedby supporting ruthenium halide on a carrier, treating the supported oneby using an alkali solution of hydrazine, adding an alkali metalchloride, and oxidizing.
 16. The process according to claim 1, whereinthe catalyst (3) is a supported ruthenium oxide catalyst obtained bysupporting a ruthenium compound on a carrier, reducing the supported oneby using a reducing hydrogenated compound, and oxidizing.
 17. Theprocess according to claim 1, wherein the catalyst (3) is a supportedruthenium oxide catalyst obtained by supporting a ruthenium compound ona carrier, reducing the supported one by using a reducing hydrogenatedcompound, adding an alkali metal chloride, and oxidizing.
 18. Theprocess according to claim 1, wherein the catalyst (3) is a supportedruthenium oxide catalyst obtained by supporting ruthenium halide on acarrier, reducing the supported one by using an alkali metal boronhydride compound, and oxidizing.
 19. The process according to claim 1,wherein the catalyst (3) is a supported ruthenium oxide catalystobtained by supporting ruthenium hydride on a carrier, reducing thesupported one by using an alkali metal boron hydride compound, adding analkali metal chloride, and oxidizing.
 20. The process according to claim1, wherein the catalyst (3) is a supported ruthenium oxide catalystobtained by supporting ruthenium chloride on a carrier, reducing thesupported one by using sodium boron hydride, and oxidizing.
 21. Theprocess according to claim 1, wherein the catalyst (3) is a supportedruthenium oxide catalyst obtained by supporting ruthenium chloride on acarrier, reducing the supported one by using sodium boron halide, addingan alkali metal chloride, and oxidizing.
 22. The process according toclaim 1, wherein the catalyst (1), (2) or (3) is a supported rutheniumoxide catalyst obtained by using titanium oxide containing not less than10% by weight of rutile titanium oxide as a carrier.
 23. The processaccording to claim 1, wherein the catalyst (1), (2) or (3) is asupported ruthenium oxide catalyst obtained by using titanium oxidecontaining not less than 30% by weight of rutile titanium oxide as acarrier.
 24. The process according to claim 1, wherein the catalyst (4)is a supported ruthenium oxide catalyst obtained by the steps whichcomprise supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing compound or a reducing agent in aliquid phase, and oxidizing, wherein titanium oxide containing an OHgroup in an amount of 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier) per unitweight of a carrier is used as the carrier.
 25. The process according toclaim 1, wherein the catalyst (4) is a supported ruthenium oxidecatalyst obtained by the steps which comprise supporting a rutheniumcompound on a carrier, treating the supported one by using a reducingcompound or a reducing agent in a liquid phase, and oxidizing, whereintitanium oxide containing an OH group in an amount of 0.2×10⁻⁴ to20×10⁻⁴ (mol/g-carrier) per unit weight of a carrier is used as thecarrier.
 26. The process according to claim 1, wherein the catalyst (4)is a supported ruthenium oxide catalyst obtained by the steps whichcomprise supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing compound or a reducing agent in aliquid phase, and oxidizing, wherein titanium oxide containing an OHgroup in an amount of 3×10⁻⁴ to 15×10⁻⁴ (mol/g-carrier) per unit weightof a carrier is used as the carrier.
 27. The process according to claim1, wherein the catalyst (4) or (5) is a supported ruthenium oxidecatalyst obtained by using titanium oxide containing not less than 10%by weight of rutile titanium oxide as a carrier.
 28. The processaccording to claim 1, wherein the catalyst (4) or (5) is a supportedruthenium oxide catalyst obtained by using titanium oxide containing notless than 30% by weight of rutile titanium oxide as a carrier.
 29. Theprocess according to claim 1, wherein the catalyst (5) is a supportedruthenium oxide catalyst obtained by the steps which comprise supportinga ruthenium compound on a carrier, treating the supported one by using areducing compound or a reducing agent in a liquid phase, and oxidizing,wherein titanium oxide containing an OH group in an amount of 0.2×10⁻⁴to 20×10⁻⁴ (mol/g-carrier) per unit weight of a carrier is used as thecarrier.
 30. The process according to claim 1, wherein the catalyst (5)is a supported ruthenium oxide catalyst obtained by the steps whichcomprise supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing compound or a reducing agent in aliquid phase, and oxidizing, wherein titanium oxide containing an OHgroup in an amount of 3×10⁻⁴ to 15×10⁻⁴ (mol/g-carrier) per unit weightof a carrier is used as the carrier.
 31. The process according to claim1, wherein the catalyst (4) or (5) is a supported ruthenium oxidecatalyst obtained by supporting a ruthenium compound on a carrier,reducing the supported one by using a reducing hydrogenated compound,and oxidizing.
 32. The process according to claim 1, wherein thecatalyst (4) or (5) is a supported ruthenium oxide catalyst obtained bysupporting a ruthenium compound on a carrier, treating the supported oneby using a reducing compound, and oxidizing.
 33. The process accordingto claim 1, wherein the catalyst (4) or (5) is a supported rutheniumoxide catalyst obtained by supporting a ruthenium compound on a carrier,treating the supported one by using an alkali solution of a reducingcompound, and oxidizing.
 34. The process according to claim 1, whereinthe catalyst system (6) is a catalyst system at least containing acomponent (A), a component (B) and a catalyst carrier component.
 35. Theprocess according to claim 1, wherein the catalyst system (6) is acatalyst made of a molding containing a component (A) and a component(B) obtained by integrally molding.
 36. The process according to claim1, wherein the catalyst system (6) is a catalyst made of a moldingcontaining a component (A), a component (B) and a catalyst carriercomponent obtained by integrally molding.
 37. The process according toclaim 35, wherein the catalyst is made of a molding containing thecomponent (A) supported on the component (B).
 38. The process accordingto claim 36, wherein the catalyst is made of a molding containing boththe component (A) supported on the catalyst carrier component and thecomponent (B).
 39. The process according to claim 36, wherein thecatalyst is made of the molding containing the component (A) supportedon a mixture of the catalyst carrier component with the component (B).40. The process according to claim 1, wherein the catalyst system (6) isa catalyst system containing both of a molding containing the component(A) and the component (B) obtained by integrally molding and a moldingcontaining the component (B) obtained by integrally molding.
 41. Theprocess according to claim 1, wherein the catalyst system (6) is acatalyst system comprising both of a molding containing the component(A) with the catalyst carrier component obtained by integrally moldingand a molding containing a component (B) obtained by integrally molding.42. The process according to claim 1 (6), wherein the component (B) isα-alumina.
 43. The process according to claim 1 (6), wherein thecomponent (A) is a component containing ruthenium.
 44. The processaccording to claim 43, wherein the component (A) is a componentcontaining ruthenium oxide.
 45. The process according to claim 44,wherein the component (B) and/or the catalyst carrier component is acomponent containing titanium oxide.
 46. The process according to claim1, wherein the catalyst (7) is an outer surface-supported catalystobtained by supporting ruthenium oxide on a carrier at the outersurface.
 47. The process according to claim 1, wherein the catalyst (8)is an outer surface-supported catalyst prepared by an alkali preliminaryimpregnation process.
 48. The process according to claim 1, wherein thecatalyst (9) is a ruthenium oxide catalyst supported on chromium oxide.49. The process according to claim 1, wherein the catalyst (9) is acatalyst obtained by calcining a ruthenium chloride catalyst supportedon chromium oxide.
 50. A process for producing a supported rutheniumoxide catalyst selected from the following processes (1) to (5): (1) aprocess for producing a supported ruthenium oxide catalyst, whichcomprises the steps of supporting a ruthenium compound on a carrier,treating the supported one by using a basic compound, treating by usingcompound, and oxidizing; (2) a process for producing a supportedruthenium oxide catalyst, which comprises the steps of supporting aruthenium compound on a carrier, treating the supported one by using areducing compound to form ruthenium having an oxidation number of 1 toless than 4 valence, and oxidizing; (3) a process for producing asupported ruthenium oxide catalyst, which comprises the steps ofsupporting a ruthenium compound on a titanium oxide carrier containingrutile titanium oxide, treating the supported one by using a reducingagent, and oxidizing; (4) a process for producing a supported rutheniumoxide catalyst, which comprises the steps of supporting a rutheniumcompound on a titanium oxide carrier containing an OH group in an amountof 0.1×10⁻⁴ to 30×10⁻⁴ (mol/g-carrier) per unit weight of a carrier,treating the supported one by using a reducing agent, and oxidizing; and(5) a process for producing a supported ruthenium oxide catalystcontaining ruthenium oxide only at an outer surface layer, not less than80% of the outer surface of said catalyst satisfying the followingexpression (1):S/L<0.35  (1) wherein L is a distance between a point (A) and a point(B), said point (B) being a point formed on the surface of a catalystwhen a perpendicular line dropped from any point (A) on the surface ofthe catalyst to the inside of the catalyst goes out from the catalyst atthe opposite side of the point (A), and S is a distance between thepoint (A) and a point (C), said point (C) being a point on theperpendicular line where ruthenium oxide does not exist, wherein saidprocess comprises supporting an alkali on a carrier, supporting at leastone ruthenium compound selected from the group consisting of rutheniumhalide, rutheniumoxy chloride, ruthenium-acetylacetonato complex,ruthenium organic acid salt and ruthenium-nitrosyl complex on thecarrier, treating by using a reducing agent, and oxidizing.
 51. Theprocess according to claim 50 (2), wherein said process comprises thesteps of supporting at least one ruthenium compound selected from thegroup consisting of ruthenium halide, chlororuthenate salt, oxyruthenatesalt, rutheniumoxy chloride, ruthenium-ammine complex, chloride ofruthenium-ammine complex, ruthenium-acetylacetonato complex, rutheniumorganic acid salt and ruthenium-nitrosyl complex on a carrier, treatingthe supported one by using a reducing agent to form ruthenium having anoxidization number of 1 to less than 4 valence, and oxidizing.
 52. Theprocess according to claim 50 (2), wherein said process comprises thesteps of supporting at least one ruthenium compound selected from thegroup consisting of ruthenium halide, chlororuthenate salt, oxyruthenatesalt, rutheniumoxy chloride, ruthenium- ammine complex, chloride ofruthenium-ammine complex, ruthenium-acetylacetonato complex, rutheniumorganic acid salt and ruthenium-nitrosyl complex on a carrier, treatingthe supported one by using a basic compound, treating by using areducing agent, and oxidizing.
 53. The process according to claim 50(2), wherein the reducing agent is a reducing compound.
 54. The processaccording to claim 50 (1) or (2), wherein said process comprisessupporting ruthenium halide on a carrier, adding an alkali to thesupported one, treating by using a reducing compound, and oxidizing. 55.The process according to claim 50 (1) or (2), wherein said processcomprises supporting ruthenium halide on a carrier, treating thesupported one by using an alkali solution of a reducing compound, andoxidizing.
 56. The process according to claim 50 (1) or (2), whereinsaid process comprises supporting ruthenium halide on a carrier, addingan alkali to the supported one, treating by using a reducing compound,adding an alkali metal chloride, and oxidizing.
 57. The processaccording to claim 50 (1) or (2), wherein said process comprisessupporting ruthenium halide on a carrier, treating the supported one byusing an alkali solution of a reducing compound, adding an alkali metalchloride, and oxidizing.
 58. The process according to claim 50 (1) or(2), wherein said process comprises supporting ruthenium halide on acarrier, adding an alkali to the supported one, treating by usinghydrazine, and oxidizing.
 59. The process according to claim 50 (1) or(2), wherein said process comprises supporting ruthenium halide on acarrier, treating the supported one by using an alkali solution ofhydrazine, and oxidizing.
 60. The process according to claim 50 (1) or(2), wherein said process comprises supporting ruthenium halide on acarrier, adding an alkali to the supported one, treating by usinghydrazine, adding an alkali metal chloride, and oxidizing.
 61. Theprocess according to claim 50 (1) or (2), wherein said process comprisessupporting ruthenium halide on a carrier, treating the supported one byusing an alkali solution of hydrazine, adding an alkali metal chloride,and oxidizing.
 62. The process according to claim 50, wherein thecatalyst (1) or (2) is a supported ruthenium oxide catalyst obtained byusing titanium oxide containing not less than 10% by weight of rutiletitanium oxide as a carrier.
 63. The process according to claim 50,wherein the catalyst (1) or (2) is a supported ruthenium oxide catalystobtained by using titanium oxide containing not less than 30% by weightof rutile titanium oxide as a carrier.
 64. The process according toclaim 50 (3) or (4), wherein the titanium oxide is titanium oxidecontaining not less than 10% of rutile titanium oxide.
 65. The processaccording to claim 50 (3) or (4), wherein the titanium oxide is titaniumoxide containing not less than 30% of rutile titanium oxide.
 66. Theprocess according to claim 50 (3) or (4), wherein said process comprisessupporting a ruthenium compound on a carrier, reducing the supported oneby using a reducing hydrogenated compound, and oxidizing.
 67. Theprocess according to claim 50 (3) or (4), wherein said process comprisessupporting a ruthenium compound on a carrier, treating the supported oneby using a reducing compound, and oxidizing.
 68. The process accordingto claim 50 (3) or (4), wherein said process comprises supporting aruthenium compound on a carrier, treating the supported one by using analkali solution of a reducing compound, and oxidizing.
 69. The processaccording to claim 50 (3), wherein the catalyst is a supported rutheniumoxide catalyst obtained by the steps which comprise supporting aruthenium compound on a carrier, treating the supported one by using areducing compound or a reducing agent in a liquid phase, and oxidizing,wherein titanium oxide containing an OH group in an amount of 0.1×10⁻⁴to 30×10⁻⁴ (mol/g-carrier) per unit weight of a carrier is used as thecarrier.
 70. The process according to claim 50 (3), wherein the catalystis a supported ruthenium oxide catalyst obtained by the steps whichcomprise supporting a ruthenium compound on a carrier, treating thesupported one by using a reducing compound or a reducing agent in aliquid phase, and oxidizing, wherein titanium oxide containing an OHgroup in an amount of 0.2×10⁻⁴ to 20×10⁻⁴ (mol/g-carrier) per unitweight of a carrier is used as the carrier.
 71. The process according toclaim 50 (3), wherein the catalyst is a supported ruthenium oxidecatalyst obtained by the steps which comprise supporting a rutheniumcompound on a carrier, treating the supported one by using a reducingcompound or a reducing agent in a liquid phase, and oxidizing, whereintitanium oxide containing an OH group in an amount of 3×10⁻⁴ to 15×10⁻⁴(mol/g-carrier) per unit weight of a carrier is used as the carrier. 72.The process according to claim 50 (3) or (4), wherein the catalyst isobtained by supporting a ruthenium halide on carrier, treating thesupported one by using a reducing compound, and oxidizing.
 73. Theprocess according to claim 50 (3) or (4), wherein the catalyst isobtained by supporting a ruthenium halide on carrier, treating thesupported one by using an alkali solution of a reducing compound, andoxidizing.
 74. The process according to claim 50 (4), wherein thecatalyst is a supported ruthenium oxide catalyst obtained by the stepswhich comprise supporting a ruthenium compound on a carrier, treatingthe supported one by using a reducing compound or a reducing agent in aliquid phase, and oxidizing, wherein titanium oxide containing an OHgroup in an amount of 0.2×10⁻⁴ to 2 0×10⁻⁴ (mol/g-carrier) per unitweight of a carrier is used as the carrier.
 75. The process according toclaim 50 (4), wherein the catalyst is a supported ruthenium oxidecatalyst obtained by the steps which comprise supporting a rutheniumcompound on a carrier, treating the supported one by using a reducingcompound or a reducing agent in a liquid phase, and oxidizing, whereintitanium oxide containing an OH group in an amount of 3×10⁻⁴ to 15×10⁻⁴(mol/g-carrier) per unit weight of a carrier is used as the carrier.76-87 (canceled).
 88. The process according to claim 43, wherein thecomponent (B) and/or the catalyst carrier component is a componentcontaining titaium oxide.